Brian Litz, ballistics expert is looking for folks that can help him document this phenomenon
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First, some background: There's a common discussion topic based on the observation that some rifles seem to shoot smaller angular groups at longer ranges, for example, 1 inch groups at 100 yards, and also 1 inch groups at 200 yards. This could also be expressed as 1 MOA at 100, and 1/2 MOA at 200. I'll refer to this as non-liner dispersion, which is anytime a rifle groups smaller MOA at farther range.
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We have a logical dilemma: "we haven't observed non-linear dispersion in any of the testing that we've done, but we still can't claim with certainty that it doesn't happen because we haven't tested every possible rifle and combination". There are still many shooters swearing they see it on a regular basis.
It's disappointing that we haven't reached a more decisive conclusion, but I'm not giving up yet. So what's the next step? Well, certainly it must be something dramatic, and involve live fire! So here it is.
The Applied Ballistics 'Shoot Thru Target' Challange I'm inviting any shooter who has a rifle which exhibits non-linear dispersion to the Applied Ballistics Laboratory in Michigan to demonstrate the effect. I'll pay your travel and hotel stay (If you successfully demonstrate the effect, I'll even pay your *return* travel as well ) The objective is to produce a repeatable example of this phenomena so it can be studied and hopefully we can learn what's going on.
This is a friendly challenge with the objective of learning. As much fun as it is to discuss all the theories online, I'd really like to actually solve this one.
2. Disturbance of bullet by release of gas at the instant of bullet boat tail exiting the crown. This is exacerbated by long bullets with long boat tails typically used in long range shooting and "magnum" cartridges that generate very high pressure at the muzzle as the bullet exits. Basically the release of extremely high pressure gas precursing around the long, barely stabilized projectile causes a bit of an "upset" to the gyroscopic stability in the first portion of the bullet flight.
Said another way; the bullet is getting smacked on the tail on the way out the door. Everything settles down once the bullet is out of the blast zone.
People have often referred to bullets "going to sleep" after a certain range....
I did not discover this nor have I collected the data that confirms. It was passed to me by a ballistician and bullet designer at a major ammunition company. I have experienced the phenomenon of less dispersion at further range many times.
2. Disturbance of bullet by release of gas at the instant of bullet boat tail exiting the crown. This is exacerbated by long bullets with long boat tails typically used in long range shooting and "magnum" cartridges that generate very high pressure at the muzzle as the bullet exits. Basically the release of extremely high pressure gas precursing around the long, barely stabilized projectile causes a bit of an "upset" to the gyroscopic stability in the first portion of the bullet flight.
Said another way; the bullet is getting smacked on the tail on the way out the door. Everything settles down once the bullet is out of the blast zone.
People have often referred to bullets "going to sleep" after a certain range....
I did not discover this nor have I collected the data that confirms. It was passed to me by a ballistician and bullet designer at a major ammunition company. I have experienced the phenomenon of less dispersion at further range many times.
Boddington has seen it,written on it. He pointed to #2 above as a cause as well.
Google "yaw", "precession", "angle of repose"and "nutation" as related to bullets in flight. (think I got those words right I was reading about it last night.
Those things (bullets) ain't always flying perfectly straight and nose on all the time
If it's a parallax issue another scope would solve it right? Do iron sights and target apertures have parallax?
As Bryan Litz points out, the phenomenon of bullets "going to sleep" doesn't explain how they somehow land closer to point-of-aim further downrange.
I'll be very interested in whether anybody takes him up on his offer of a free trip to his test-lab with such a rifle. It appears several people who've posted on this thread own one.
I'll be very interested in whether anybody takes him up on his offer of a free trip to his test-lab with such a rifle. It appears several people who've posted on this thread own one.
Physics, it aint for everyone... It would take a bullet that has eyes...
The reason that I am skeptical about this is that in order for this to happen, the bullets that get pushed a little too far right would somehow halve to know to make a slight left turn when they settle down, the bullets that went left would have to know to turn right, the bullets that got pushed too low would have to somehow turn up, and so on.
Some of the explanations floated so far such as statistics (a rifle will shoot some small groups and some larger groups, and it's likely you'll see some smaller groups when you shoot far, and some larger groups when you shoot close), parallax, and aiming error due to target size.
All these would be eliminated by Litz' test setup which would measure the path of the same bullets as they cross the short line, then continue on to print at the long line.
If you have some time on your hand, read the original thread (link in the original post here). I found it a good read. C'mon folks, if you have such a rifle, you would be contributing to expanding the understanding of exterior ballistics...(and as Mule Deer had mentioned, would score a trip to spend time on the range with one of today's true ballistics experts)
Except that it is a physical impossibility. How people don't just take about 30 seconds and think about the thing is amazing. Once a bullet or anything has been launched at a certain angular deviation, it can't correct itself and become a smaller angular deviation. There are a multitude of reasons why people believe that they see groups getting smaller at longer ranges, but it isn't because the bullet "goes to sleep".
I've worked at a place with the same targets that Bryan is talking about. Of course just a bit of critical thinking would reveal that there is no way for a bullet to have 2 MOA say of angular deviation at 100 yards, but magically have 1 MOA deviation at 300 yards, but using those target systems and shooting through several of them simultaneously reveals of course that groups can only get larger as distance increases, not smaller.
Over the years, I've participated in many discussions about this phenomenon. The only credible bit of evidence that came up in support of the phenomenon was a posting by Gale McMillan on the old usenet recguns forum, which I believe was archived on yarchives. Mac described observing just such an effect while testing the 50 cal Sniper Rifles he produced for the military. I've searched high and low for that old posting recently, and can't find it now. Maybe someone with stronger Google-Fu than I will unearth that gem.
I forgot to add that there's another credible explanation for the effect manifesting in the vertical plane only called Positive Compensation.
BTW, I proposed acoustic targets when the Oeler's became available on the consumer market, but I think he's using old fashioned paper for the midrange.
I did not discover this nor have I collected the data that confirms. It was passed to me by a ballistician and bullet designer at a major ammunition company. I have experienced the phenomenon of less dispersion at further range many times.
What if the blast at the muzzle is not upsetting the stability of the bullet or its angle of dispersion but is just nudging the stable bullet off line slightly?
A perfectly straight launched bullet nudged over/up/down .001" would cause some of the "MOA shrinkage" at longer range. Something like that could cause a .75MOA group at 100 to go on to be a .5MOA at 300. Once the bullet is out of the blast zone there is no other force but wind and air pressure to act on it.
Reading that prompted me to dig out my copy of Dr. Mann's book, where he performed the exact experiment as described by Litz. The results are as expected - linear - but the measured distances were short (100 & 175yds) and the number of tests small. Personally, I'd be listening to Gale McMillan on this kinda stuff.
Sure do miss recguns. The quantity and quality of info passed around from the likes of Bart Bobbit, Gale McMillan, etc. was just incredible.
I suspect (but don't know) the reason Bryan's using paper targets is a lot of people wouldn't believe acoustic targets. Results from an Oehler 43 would be regarded much like posts on the Campfire that don't include "pitchers."
I am, again, amazed that the entire shooting industry hasn't tapped the Campfire as a resource. There are more confirmed ballistical anomalies and shooter expertize here than most magazines and books put together.
Aside from all that shared knowledge, I have managed to take stock rifles that don't print tiny groups and don't have fast twist, and still hit stuff. Color me skeptical...
Except that it is a physical impossibility. How people don't just take about 30 seconds and think about the thing is amazing. Once a bullet or anything has been launched at a certain angular deviation, it can't correct itself and become a smaller angular deviation. There are a multitude of reasons why people believe that they see groups getting smaller at longer ranges, but it isn't because the bullet "goes to sleep".
I've worked at a place with the same targets that Bryan is talking about. Of course just a bit of critical thinking would reveal that there is no way for a bullet to have 2 MOA say of angular deviation at 100 yards, but magically have 1 MOA deviation at 300 yards, but using those target systems and shooting through several of them simultaneously reveals of course that groups can only get larger as distance increases, not smaller.
Of course I don't know squat, and ain't much of a top notch shooter, but I can certainly tell you that without a doubt, the worked up 600-1000 yard load in my ARs with 90 jlks, will not group worth a flip at 300 yards. It wins matches at 600 and beyond. It looses matches at 300. So much so that I had to start carrying my 75 amax ammo to some matches that would cancel the full 600 yard stage if not enough folks were around, and shoot 300 yard reduced.... I did that a few times, and once in bad wind thinking the 90s would win the match for me due to really bad winds.... They did not. I changed ammo after about 5 shots.
I can say this, the ammo appears to basically hold a bit over MOA at 300, and very much so sub moa down to around .5 MOA repeatable over the course of many rounds and a many years of shooting this ammo. At least 5 years of shooting almost year round.
RE parallax... unless we had it with iron sights I can't blame it on that.
My theory has always been, not totally stable. Of course when working on 600 yard ammo, I started at 600... was suprised the first time I used it in a 300 yard match that it sucked really badly.
I have seen this same ammo many years before in a slightly faster twist, IE 6.5/7 twists the 7 would net you just the tiniest oblong hole at 100... but then I realized you are wasting your time developing loads at 100, when you are going to shoot them at 600, and promptly set up a 600 yard bench at my house.
While I have no "scientific" answer to this, I can tell you without a doubt to my eyes it exists.
And I could care less why, I just learned quickly where to use what ammo.
Paper has always been the final answer for me, though I"d include acoustical, but its about results, not what it "should" or should not do or calculate out to...
"LONG RANGE TUNE.... Here is an interesting set of trajectory plots. No matter how carefully one loads his ammo, there are going to be small differences in muzzle velocity. Consider a load with an average muzzle velocity of 2915 fps with a muzzle velocity variation of 15 fps. Then consider this load tuned for zero vertical at 100 yards that overcomes that small difference in muzzle velocity. This same load will be out of tune by 73.23-71.50=1.73 inches of vertical at 600 yards. However if the load is tuned so that there is 12.21-11.92=0.29 inches of vertical at 100 yards (with the slower muzzle velocity hitting higher) then there would be zero vertical at 600 yards. This chart is for a 6.5mm 140 gr VLD bullet with a 0.64 BC. A similar chart or table can be made for each long range load. If you are in tune for zero vertical at 100 yards, you will not be in tune for zero vertical at 600 or 1000 yards."
...Jeff, I forgot to mention the other credible example of the phenomenon in your experiences. I'll hope that you consider taking Litz up on getting up to Michigan so he can try to figure out the "why" of the happening.
I bet if there was a group of chicks at 100 yds, and Dogshooter starting walking toward them, that 100 yd. group size would shrink significantly due to dispersion....
"LONG RANGE TUNE.... Here is an interesting set of trajectory plots. No matter how carefully one loads his ammo, there are going to be small differences in muzzle velocity. Consider a load with an average muzzle velocity of 2915 fps with a muzzle velocity variation of 15 fps. Then consider this load tuned for zero vertical at 100 yards that overcomes that small difference in muzzle velocity. This same load will be out of tune by 73.23-71.50=1.73 inches of vertical at 600 yards. However if the load is tuned so that there is 12.21-11.92=0.29 inches of vertical at 100 yards (with the slower muzzle velocity hitting higher) then there would be zero vertical at 600 yards. This chart is for a 6.5mm 140 gr VLD bullet with a 0.64 BC. A similar chart or table can be made for each long range load. If you are in tune for zero vertical at 100 yards, you will not be in tune for zero vertical at 600 or 1000 yards."
This blew my mind. Way above my level of ballistics understanding!
I've seen non-linear dispersion on targets between close range and longer range. Nothing so drastic as 1 moa at 100 and the same at 200, but a load that shoots a consistent .7 moa at 100 and then .5 moa past 300. Could simply be shooter error, or other variables unaccounted for. Have only seen this with very long VLD-style bullets.
I don't think the linear dispersion model works with something spinning so fast, as that introduces an entirely different physics to the flight of the projectile in an atmosphere.
This thread reminds me of other physical 'impossibilities' that were later proved very possible, like a human running a 4-minute mile. There are many such examples. We as a race seem to have become very egotistical about what we 'know'.
If I could get past a few hurdles, I'd be tempted to take Litz's offer. Hoping someone does, because I do want to learn.
Clark, I read your post before you edited it. I only know recguns from the yarchives, but Gale McMillans posts are very present there (as are BartB's.) Yes, I did frequent Shooters.com (mostly the Highpower board). There were some very cool discussions there (some of which like the pressure measurement discussion, I saved as pdf's and mht's). I'm not much of an optics guy but I do have a small collection of External adjust Unertl's, Remingtons, Lymans etc. I think I remember you from the old Accurate Shooter site... ClarkM, engineer from the PNW?
There are a few ways that quantum mechanics could also play a part in explaining what is going on with non-linear dispersion. I keep wondering if that can somehow be experimented with. I know a lot of people prefer the Newtonian physics model, even though it has been surpassed in accuracy by the Quantum model.
What if the blast at the muzzle is not upsetting the stability of the bullet or its angle of dispersion but is just nudging the stable bullet off line slightly?
A perfectly straight launched bullet nudged over/up/down .001" would cause some of the "MOA shrinkage" at longer range. Something like that could cause a .75MOA group at 100 to go on to be a .5MOA at 300. Once the bullet is out of the blast zone there is no other force but wind and air pressure to act on it.
One of these two illustrations should help as well. The first is very important.
Some prefer this explanation of the phenomena. I like this angle of dispersion, but think the the muzzle blast would definitely cause shrinkage well after the fact. Adding some Yaw will help if you don't seat the projectile concentrically
Its not in the cards for me to get to MI at this point in my life.
But there is always the next 9 years of slavery and then retirement.... then it could happen.
Now that I"ve read some more....
I may not recall exactly, but what drove me nuts was with the 90s, it would seem you could work a group down to around 3 inches at 600. 5 shot and 10 shot groups would be about the same, this after a LOT of shooting groups to confirm and running lots of 10+1 and 10+1 tests at 600 out of the sling in 22 shot matches(yes that didn't follow rules to a T....)
BUT IIRC the 90s also held about the same 3 inch group at 300 that they did at 600.
I"d bet the 300 yard group shot over time might be more like 2.5 inches and the 600s might even average a bit larger than 3 but for all practical purposes it was the same. 3 at 600 is fine. 3 at 300 is puke.
Please wish the family Merry Christmas from Carolyn and I!
This diagram can clear up a bunch of confusion, it was a test done a few years ago and helps qualify some misunderstood ballistic phenomenon...
Obviously the flaw there is use of too much powder, making the projectile rise after leaving the bore. The pressure required to match that graph is generally to hard on the bullet bases and will knock the accuracy out of the park so that it really doesn't matter that its rising instead of falling.
Thankfully mine generally does fall after its risen, but it has a useful half life in there long enough to make me happy... but I digress
That would not be a big deal, unfortunately I don't have those anymore.
Damn it I wish I did. I have some uppers left but both 90 uppers were shot out, all I have is capable by the 7 twist and 75/80s and those never really showed that much to me. It would to an extent by a small margin but nothing enough to scratch my head over.
I was buying scopes from you out of shotgun news in the 90s. Last year I bought this rifle from your company. Right now I am ordering from you Weaver S46 and S54 bases to mill off the radius on the bottom to put on these Dumoulin receivers I bought:
Did someone says something about quantum mechanics? I am wondering if human observation decreases entropy, and so causes electron or photon "waveform collapse".
�When you have eliminated the impossible, whatever remains, however improbable, must be the truth,� said Sherlock Holmes.
Clark, Your original unedited post was a nice trip down internet memory lane. But I would not be the scope peddlin' ChrisF...(although I do have some definite opinions about spotting scopes!)
Ironically, if you check the yarchive.net site of usenet archives, you'll find that Gale McMillan was quite the optics tinkerer/entrepreneur.
Did someone says something about quantum mechanics? I am wondering if human observation decreases entropy, and so causes electron or photon "waveform collapse".
I'm actually thinking "string theory"...but I keep asking myself, how long a piece of twine do you need to pull the bullet back on course?
I just read the wikipedia page on string theory. That did not do me any good. The room is still spinning.
~ 15 years ago I got some emails from Gale about scopes. That was 5 computers ago, so all we have is my poor memory.
He suggested I buy Leupold and Bausch and Lomb. That is all I remember right now. I blame the bad memory function on that wiki page. But I remember a lot of his post about going to Asia for his scope contract with the Marines.
My father got a couple contracts with the marines. The XM70 is the only one with internet exposure now. He was proud of the constant recoil over 6 shots he got. http://www.liveleak.com/view?i=511_1347383868
Clark is that a B78? BTW, I think you're supposed to shred those files, not shoot them...and BBTW, I think you shot your chrono too! It looks like it keeled over!
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I am wondering if human observation decreases entropy, and so causes electron or photon "waveform collapse".
I think it's a truism that "human intervention decreases entropy"...but the real question is whether pulling the string or pulling my finger will get the bullet back on course?
Remember, the objective at this point is to determine, experimentally, IF group convergence happens as claimed. If it does, THEN we can have long discussions about how it happens. Typically, the internet discussions put the cart before the horse and there are many discussions/arguments about how it happens with little effort spent to determine IF it really happens in the first place.
That's the intent of the Applied Ballistics Shoot Thru Target Challenge.
If extensive live fire testing shows that group convergence isn't really happening, then we can have far more productive discussions about what really IS happening, and how to address it.
Please spread the word about this challenge to anyone you know that believes in converging groups. The shoot thru target will either convert them, or demonstrate the phenomena to be real. Either result would be progress from where we are now.
BTW, I think you're supposed to shred those files, not shoot them...
Shooting is the proper method here.
Lest one could be labeled a shredophile.
I admit to squeezing a few triggers of a few guns at LR in my day. I have never, ever, ever, had a rifle that shot tighter groups further away. Ever.
To be honest, the mere thought of it makes no sense and I would immediately call BS when hearing of such a report.
That said, I used to be an avid reader of anything Gale McMillan I could find. He didn't guess at stuff much. Needless to say, I find his post to be, at the very least, thought provoking.
However, and forgive me if I did not do a thorough enough job reading this thread, I'm assuming that nobody has ever actually been able to PROVE the bullet path to be anything but directly lineal?
However, and forgive me if I did not do a thorough enough job reading this thread, I'm assuming that nobody has ever actually been able to PROVE the bullet path to be anything but directly lineal?
No, it's never been proven/demonstrated. That's what the 'challenge' is about.
It's commonly reported that a shooter/rifle will generate smaller MOA groups at longer ranges; HOWEVER, the true cause has never been discovered. Some people believe the bullets actually fly that way, others believe optics, or statistical chance is the cause. The intent of the shoot thru target is to discover if bullets actually fly that way. So far, based on dozens of groups fired from .224 thru .408 cal, they haven't.
Have not tried your tall target test yet due to limited time. But I soon will be. Great application of ivory tower math to real world stuff. Glad to see you posting here.
I have always thought this to be the answer to tiny groups at 300 but so so at 100. Improper adjustments of the parallax. My good friend espouses the bullet going to sleep idea, (gyroscopic procession???) but I don't buy it.
I have always thought this to be the answer to tiny groups at 300 but so so at 100. Improper adjustments of the parallax. My good friend espouses the bullet going to sleep idea, (gyroscopic procession???) but I don't buy it.
I"ve never asked, but is parallax present in irons, thats all we ever shot in competition....
I don't think there can be parallax with irons, but it would be the same as bad sight alignment.
To be clear on stability and bullets 'going to sleep'... It's completely normal for bullets to come out of the muzzle with some disturbance or 'tip off' due to barrel whip, gas escape, imbalance, etc. When this happens, a stable bullet will settle and dampen it's yaw down as it flies.
However, the helical/corkscrew flight path that results from this motion is so very minor (about 1/10th of one caliber) that it simply doesn't explain the magnitude of group convergence that is often reported.
I don't think there can be parallax with irons, but it would be the same as bad sight alignment.
To be clear on stability and bullets 'going to sleep'... It's completely normal for bullets to come out of the muzzle with some disturbance or 'tip off' due to barrel whip, gas escape, imbalance, etc. When this happens, a stable bullet will settle and dampen it's yaw down as it flies.
However, the helical/corkscrew flight path that results from this motion is so very minor (about 1/10th of one caliber) that it simply doesn't explain the magnitude of group convergence that is often reported.
Jeff, Re: parallex with irons. There's a fellow competitor/engineer a similar question and posted a white paper. I think he was challenging the importance of sight alignment. I'll see if I can find a link...or try googling Robert Burge, iron sights.
Jeff, Re: parallex with irons. There's a fellow competitor/engineer a similar question and posted a white paper. I think he was challenging the importance of sight alignment. I'll see if I can find a link...or try googling Robert Burge, iron sights.
Thats all it is in optics... non alignment.
Without that with irons you can't shoot a group. Pretty simple.
Since I could shoot gropus in the day, and according to some laser thingy my prone slung up wobble was very minimal, I'd think my results of shooting were repeatable enough.
Damn shame, you are getting me itchy again, but it simply won't happen unfortunately....at least not for some years.
BTW, I still have two 6.5 twist uppers. One is set up for strain pressures. (remember that one?) and the other has maybe 2000 rounds on it. Would you want me to send one of them to Texas for 90JLK load work-ups to see if you can recreate the effect with my upper?
I have an early 56 or 57' Winchester Varminter in .243, I noticed it loved federal prem70 gr BT's, I was able to buy the last 9 boxes left from the case of the first box that shot so well.the gun and ammo was sub moa at 100 about a solid .75 inch 5 shot on clear ,cool and calm days.At 300 yards it would and still will shoot 1 1/8" group if I am 'on'. I have 3 boxes,60 rounds left and smile every time I see them in the back of the ammo storage.. As hard as I have tried I just can tie the 300 yard 5 shot groups at 200 yards. Old timer shooters explained it to mr as the bullets going to sleep out past the 100 yards, I never questioned I just smiled the old school gun and factory ammo will still 'do it' if Im on! very best WinPoor old50,1,2and300yardrange,
I have a 243 with a 1-8 inch twist #3 bartlein barel, shooting 105 gr berger hybrids. Have shot a 243 for 20 years, but this is a new barrel, about 6 months old. It shoots .5 to .6 at 100 yds.What is interesting is that it shoots the same group size, at 200yds. It simply doesn't change. Have replicated this 3 times now. You would think that the group size should increase as distance increases. Have not shot a bench group at 300 to see there. Any thoughts?
BTW, I still have two 6.5 twist uppers. One is set up for strain pressures. (remember that one?) and the other has maybe 2000 rounds on it. Would you want me to send one of them to Texas for 90JLK load work-ups to see if you can recreate the effect with my upper?
Thanks for that article and the one below, I'll have to make time to read it.
I appreciate the upper offer, but my life simply does not have time to do things like this right now. Vol Fire/EMS burns most of my time that I have to spare. Even find it hard to find time to work up a hunting load for a new rifle or even bed and work on the trigger.... Unfortunately between that, caring for parents, the 100 acres maintenance, and a job that is requiring more schooling and so on... just isn't time right now.
1) Watch arrows in slow motion as being released from a bow. They come out with lots of side to side movement but, they stabilize the further out they get, to a point, when they again become unstable, I believe due to a loss of spin. If you shoot one up in the sky by the time they come down they are wobbling. They start out wobbling, they stabilize, then they begin again as spin drops off.
2) Remove twist and shoot a projectile out of a smoothbore and what differences do you see? I suspect chaos.
3) Spin a toy top on a table and what happens?
I have no problem seeing a bullet stabilizing due to the SPIN relentlessly trying to "center" it, and not necessarily at OUR arbitrary 100 yards. With barrel weights, lengths, twists, construction, and projectile construction, weight, and velocities I would imagine there would be too many variables to predict at what range a given load would be the most "accurate" or centered.
The experiment that needs to be conducted is what happens to a projectile at varying rates of twist, right down to no twist. That would shed some light on things.
As Bryan Litz points out, the phenomenon of bullets "going to sleep" doesn't explain how they somehow land closer to point-of-aim further downrange.
Exactly, I never could understand why this line of reasoning still continues to exist.
I had a rifle that was shooting 300 yd groups that were consistently larger than they should have been. The culprit was when In focus at 300 yds the parralax was way off. I fixed the issue by adjusting the parralax out of the scope first then focused the eye peice. I believe 99% of this phenomenon is a parralax issue or related to a mirage issue caused by optics or even ones own eyes.
Watch this 7 second video. If you think arrows only fly worse after they leave the bow, in ever widening circles, you would be wrong.
Again, no critical thought. Think about it. Yes the arrows are flexing, but no one, and I do mean NO ONE in archery competition thinks that a bow will shoot smaller groups at 20 yards than at 10 yards. Nor if they are tuned right will they shoot smaller groups at 40 yards than at 20. And then think about that a bullet ain't flexing. It is launched from the muzzle in a particular direction. It can't magically pull itself back into the bore line.
As Bryan Litz points out, the phenomenon of bullets "going to sleep" doesn't explain how they somehow land closer to point-of-aim further downrange.
Exactly, I never could understand why this line of reasoning still continues to exist.
I had a rifle that was shooting 300 yd groups that were consistently larger than they should have been. The culprit was when In focus at 300 yds the parralax was way off. I fixed the issue by adjusting the parralax out of the scope first then focused the eye peice. I believe 99% of this phenomenon is a parralax issue or related to a mirage issue caused by optics or even ones own eyes.
Shod
Then explain why I saw it when shooting irons only...
Mirage could be, but you can read the mirage and what its doing through a spotting scope between shots...
No human could run a mile in less than four minutes until Roger Bannister did it. Scientists had proved it physically impossible, and proclaimed it loudly.
Certainly, I think Litz will get to the bottom of this question, because he is committed to the process of learning new things. Until then, I am not going to dismiss out of hand what others are reporting, and what I have seen to some extent. Ignorance is not a defensible position for claims of fact.
I have an early 56 or 57' Winchester Varminter in .243, I noticed it loved federal prem70 gr BT's, I was able to buy the last 9 boxes left from the case of the first box that shot so well.the gun and ammo was sub moa at 100 about a solid .75 inch 5 shot on clear ,cool and calm days.At 300 yards it would and still will shoot 1 1/8" group if I am 'on'. I have 3 boxes,60 rounds left and smile every time I see them in the back of the ammo storage.. As hard as I have tried I just can tie the 300 yard 5 shot groups at 200 yards. Old timer shooters explained it to mr as the bullets going to sleep out past the 100 yards, I never questioned I just smiled the old school gun and factory ammo will still 'do it' if Im on! very best WinPoor old50,1,2and300yardrange,
Sir,
I'm very interested in having you visit my lab in Michigan to demonstrate this rifle on my shoot thru target. capturing the same group at two ranges is the only way to know for sure if the bullets actually fly that way, or if something else (like optics) explains your observations.
Please email me at: [email protected] if you're interested in a paid trip to my facility.
I have a 243 with a 1-8 inch twist #3 bartlein barel, shooting 105 gr berger hybrids. Have shot a 243 for 20 years, but this is a new barrel, about 6 months old. It shoots .5 to .6 at 100 yds.What is interesting is that it shoots the same group size, at 200yds. It simply doesn't change. Have replicated this 3 times now. You would think that the group size should increase as distance increases. Have not shot a bench group at 300 to see there. Any thoughts?
Please email me: [email protected] if you're interested in a paid trip to my lab in Michigan to demonstrate this effect on my shoot thru target.
I am just back from Kansas, where I checked zero in an M-70 BOSS 30'06. This rifle will shoot a composite 100 and 200 yard group of about one and a half inches. (4.5" high at 100 and about the same at 200 for about a 285 yard zero)
The 300 yard target showed an inch and a half low for a three shot group of 1 1/8" about .4MOA.
Nothing special WW brass Varget and 150 TSX. Same gun and BOSS setting shoots similar size groups with 220 HDYs and too much RE22. Scope is a beat up VXIIc. Only two loads tried in the gun. I am so ashamed.
I am just back from Kansas, where I checked zero in an M-70 BOSS 30'06. This rifle will shoot a composite 100 and 200 yard group of about one and a half inches. (4.5" high at 100 and about the same at 200 for about a 285 yard zero)
The 300 yard target showed an inch and a half low for a three shot group of 1 1/8" about .4MOA.
Nothing special WW brass Varget and 150 TSX. Same gun and BOSS setting shoots similar size groups with 220 HDYs and too much RE22. Scope is a beat up VXIIc. Only two loads tried in the gun. I am so ashamed.
Are you interested in a paid trip to the ballistics lab to demonstrate this rifle? I'll be happy to pay your way in exchange for witnessing a working example of group convergence, which is what I understand you're seeing (1.5" groups at 100 and 200, and 1 1/8" groups at 300)
Let me know if you're able to visit and we can start making arrangements.
I"m really sorry you didn't do this 10 years ago! Or that I had not shot out those uppers on the AR that would do it.
I've not seen it with anything much other than happenstance, excepting the 90 jlks with 6.5 twist. I did run them in 7 twists and they would lightly keyhole, so I'm still saying not totally stabilized and "asleep" until they get further on out there.
I do hope that you get some responses from some of the folks here though, it sure seems like you have access if they are willing, to see whats going on.
I have two 30'06 rifles that do this. Very generous offer there Bryan... especially as airfare from Alaska is a bit salty. That said it occurred to me that maybe just maybe a shooter is a bit stressed at long range and through nature better able to perform (shoot as it were). I shoot trap a bit better in a league than in a practice session, and I shoot silly better demonstrating a drill before students...that is good stress! So parallax...sure and or just a little better ability due to stress factors ???
I do hope that you get some responses from some of the folks here though, it sure seems like you have access if they are willing, to see whats going on.
No one will take the test, because it would prove them wrong
"I don't see anyway possible for dispersion to 'recover'."
The way I understood the concept of a bullet going to sleep was that the bullets path was also a spiral rotating around the bore centerline. I guess the thought is that it spirals further from the centerline at first and then as it gets further out the bullet spirals closer to the bores centerline. So according to this theory a group could be smaller at a further range than a closer one.
I too have been led to believe that a spiral is what happens. I have witnessed increasing accuracy with boattail projectiles in both 303 and 308 cartridges. I was told that this can happen (with boattails in particular) because the gas escaping at the muzzle as the bullet leaves the barrel will push/pull the base of the projectile and ever so slightly cause the bullet to cant (a boattail design presents a long surface for the escaping gas to act upon, and maybe the effect is more like lift generated like airflow over a wing). The rapid spin rate then corrects the cant gyroscopically but results in the spiral (a force acting in another plane) that luckily dissapears.
I never did fully understand this but accepted the "gist of it". It's a bit like holding the axle of a spinning bicycle wheel out in front of you and then trying to turn it, say, to the left, and then having the whole wheel twist is another direction (eg the top of the wheel will try and go to the right which will lift your left hand and push down your right hand - a reaction 90 degrees to that of what you tried to do with the wheel in the first place).
No, bullets do NOT start out traveling in a corkscrew, then settle down to fly in a straight line. Instead, the NOSE--and base--of the bullet wobble in a corkscrew as it comes out of the muzzle, but the center of the bullet travels in a straight line.
Charts of the nose wobble have given some people the impression that the entire bullet is somehow circling around a centerline, but that is most definitely not the case. Instead, for a little while it wobbles like a poorly-thrown football. That's it, not a spiral path like a kudu horn through the air.
Sorry, can't agree with that for two reasons: 1. If the nose and base weren't aligned, the holes in the target wouldn't be round (but they are). 2. If the nose was always centred, then this dispersion discrepancy would not exist in the first place - instead we would have consistent dispersion except with oblong holes in the target at closer ranges.
A spinning top is not an entirely good analogy but it does demonstrate where the corkscrew effect would come from - except the tops spinning axis is not perpendicular to the surface it is spinning on.
Sorry, but the nose wobble is very small, and settles down very quickly. You won't be able to see any evidence from the holes in most targets, except perhaps slightly at close range, but it has been proven many times. It's a basic fact of rifle ballistics. So once again, no, bullets do NOT travel in a spiral path.
So far nobody has proven any "dispersion discrepancy" with groups from the SAME shots at different ranges, and Bryan Litz has not been able to reproduce that in any of his tests. This is why he's offering to pay the travel expenses for anybody and their rifle that does this. He's trying to find out if there's some reason for it other than scope parallax.
Once liberated from the confines of the barrel, a bullet spins around its center of mass. Sometimes that doesn't lie on the bullet's geometric center. When this is the case, the bullet moves laterally as soon as it exits the barrel (lateral throw off), and then spins around its center of mass for the duration of is flight. This, I think, is where the idea of a bullet corkscrewing comes from. A bullet such as this does indeed 'corkscrew' as it flies. However, it is only a very, very tiny amount because even the most horribly imbalanced bullet cannot have a center of mass that lies outside itself.
Bryan, I hope you are able to find a some folks who experience the phenomenon of decreasing angular dispersion, that will come to your lab, so you can investigate the observation further.
Well I have certainly seen it when using open sights (peep sights actually) - full bore event out to 1000m using both 303 and 308. I've only noticed it at shorter ranges (up to 300m) because wind starts having more noticeable affects at ranges beyond this, where I used to shoot.
I've spoken with a few full bore shooters from earlier days (before I ever started shooting) and it was commonly accepted to be a real phenomena - they used to shoot 174gn boattails (long boattail) out of their 303s using peep sights.
I know a bullet travelling in a spiral seems ludicrous, but a wobble in one plane would turn into a circular wobble with a spinning bullet which results in a corkscrew as it travels downrange. There's really no other way to explain it.
So I've seen SMLEs do it with 174gn boattails, M14s do it with 144gn boattails and my Remington 700 will do it with 155gn boattails (PALMA projectile). My M14 used to shoot 2" groups at 100yds, 2.5" groups at 200yds and 3" groups at 300yds fairly consistently (if I did my part) with the peep sight. My Remington is a bit different and will be MOA out to 200yds then sub-MOA (0.85MOA) at 300 yards.
So I've seen SMLEs do it with 174gn boattails, M14s do it with 144gn boattails and my Remington 700 will do it with 155gn boattails (PALMA projectile).
So I've seen SMLEs do it with 174gn boattails, M14s do it with 144gn boattails and my Remington 700 will do it with 155gn boattails (PALMA projectile). My M14 used to shoot 2" groups at 100yds, 2.5" groups at 200yds and 3" groups at 300yds fairly consistently (if I did my part) with the peep sight. My Remington is a bit different and will be MOA out to 200yds then sub-MOA (0.85MOA) at 300 yards.
If you can spare the time, I'll cover the expense of your travel to MI to demonstrate this. My shoot thru target is 100-300 yards, and will show if the bullets actually fly that way or not.
No disrespect, and I'm not questioning your observation. I've just been unable to observe this happening with everything I've tried (and I've tried a lot).
So I've seen SMLEs do it with 174gn boattails, M14s do it with 144gn boattails and my Remington 700 will do it with 155gn boattails (PALMA projectile). My M14 used to shoot 2" groups at 100yds, 2.5" groups at 200yds and 3" groups at 300yds fairly consistently (if I did my part) with the peep sight. My Remington is a bit different and will be MOA out to 200yds then sub-MOA (0.85MOA) at 300 yards.
If you can spare the time, I'll cover the expense of your travel to MI to demonstrate this. My shoot thru target is 100-300 yards, and will show if the bullets actually fly that way or not.
No disrespect, and I'm not questioning your observation. I've just been unable to observe this happening with everything I've tried (and I've tried a lot).
-Bryan
No offence taken - I'm keen to see the issue examined too.
The only rifle I have now of the ones I've mentioned above is my Remington.
I would love to take you up on your offer but I live in Australia.
Many of the older full bore shooters (100-1000yards, 303SMLEs, open sights - peep) over are familiar with the effect, although none know the explanation (who does?).
I think the style of the boattail makes a big difference to the effect. The 174gn 303 projectile had a rather long boattail. I have one lying around here somewhere and will try and find it and take a photo. I believe the boattail is the critical factor and does not depend too much on the rifle.
You probably have tried many boattail projectiles?
Edit - Found an image of the older style 174gn projectile:
the 100 and 200 yard records are not remotely lineal.
Those records don't tell you much since they are different shooters, and different guns.
I notice none of the groups are smaller at longer distances, but it still really doesn't address the claims here about a particular gun being "more accurate" at long range than at shorter range.
Someone who owns one of these magic rifles needs to do the test to prove the phenomenon
OK, just recalled a small factor at least with the M700 as it lives in AK (the BOSS M70 lives in KS).
Since the 700 is zeroed at 300 yards...I have a test target, 3 @300 3@200 3@100 and just one at 50 yards so that my hold under data are more factual not what some table says...anyway the 50 yard hole is about a half inch right, the 100 still a fuzz right but kind of superimposed 4-5" high over the 200 yard...but the 100 is surly, just a fuzz, right.(125 gr. ballistic tips)
I shoot the BOSS gun even less as I have a limited supply of cartridges in the cupboard in the 'Shack. The earlier mentioned 2014 11/8" 3 shot @ 300 yard zero check. In the 2013 Fall (in the BOSS gun,) I shot one @300, 1@200 and 1@50. If I connected the holes with a marker, it would be a curved line. (150 gr. Xs)
I really think it is parallax and by golly, I surprise myself every now and again shooting out there a ways. I can live with that.
the 100 and 200 yard records are not remotely lineal.
Those records don't tell you much since they are different shooters, and different guns.
I notice none of the groups are smaller at longer distances, but it still really doesn't address the claims here about a particular gun being "more accurate" at long range than at shorter range.
Someone who owns one of these magic rifles needs to do the test to prove the phenomenon
Snyper, I agree regarding same gun, same load, same shooter. The fact still remains that the 5x5 aggregates at 100, 200, and 300yds. are not even remotely lineal. I have no background in BR but this obviously raises questions. The numbers are statistically more significant in many ways. As a general statement, "the further a bullet travels and the longer the time it spends in the air, the more it will be affected by environmentals" is a generally accepted premise. So what produces the trend in the groups? It's easier to shoot at longer yardage? Probably not. As the yardage gets longer the shooters get luckier. I don't think so. It's easier to misadjust parallax at Shorter yardage. Maybe but I don't think so.
And it is a safe bet that they have the parallax sorted out too. I don't think benchrest shooters would be keen to shoot groups with a scope giving them parallax error at the distance they are shooting at.
the 100 and 200 yard records are not remotely lineal.
Those records don't tell you much since they are different shooters, and different guns.
I notice none of the groups are smaller at longer distances, but it still really doesn't address the claims here about a particular gun being "more accurate" at long range than at shorter range.
Someone who owns one of these magic rifles needs to do the test to prove the phenomenon
Snyper, I agree regarding same gun, same load, same shooter. The fact still remains that the 5x5 aggregates at 100, 200, and 300yds. are not even remotely lineal. I have no background in BR but this obviously raises questions. The numbers are statistically more significant in many ways. As a general statement, "the further a bullet travels and the longer the time it spends in the air, the more it will be affected by environmentals" is a generally accepted premise. So what produces the trend in the groups? It's easier to shoot at longer yardage? Probably not. As the yardage gets longer the shooters get luckier. I don't think so. It's easier to misadjust parallax at Shorter yardage. Maybe but I don't think so.
You see my dilemma.
All time records are, by definition, anomalous events. It would be unwise to make general judgments from them.
No, the aggregate figures are based on a collection of data and are statistical. Don't look at the other figures, look at the aggregates, as pointed out earlier.
I agree, aggregates are better to look at than records, records being anomalies as stated above.
Having said that, something to consider about the records listed in the link above is that (I'm 99% sure) the numbers are normalized to 100 yards. In other words, the records are reported in MOA not absolute inches. That's why you can have a single number represent an average for multiple ranges.
Example: Walt Berger, 5 10-shot groups at 100, 200 & 300, record is 0.3555. Not inches, but normalized to 100 yards.
I've seen BR match results reported this way, and I'm almost certain that's how these records are reported.
So, looking at it that way, the records are indicating (in almost every case) that the longer distance groups are proportionally larger than closer range groups.
the 100 and 200 yard records are not remotely lineal.
Those records don't tell you much since they are different shooters, and different guns.
I notice none of the groups are smaller at longer distances, but it still really doesn't address the claims here about a particular gun being "more accurate" at long range than at shorter range.
Someone who owns one of these magic rifles needs to do the test to prove the phenomenon
Snyper, I agree regarding same gun, same load, same shooter. The fact still remains that the 5x5 aggregates at 100, 200, and 300yds. are not even remotely lineal. I have no background in BR but this obviously raises questions. The numbers are statistically more significant in many ways. As a general statement, "the further a bullet travels and the longer the time it spends in the air, the more it will be affected by environmentals" is a generally accepted premise. So what produces the trend in the groups? It's easier to shoot at longer yardage? Probably not. As the yardage gets longer the shooters get luckier. I don't think so. It's easier to misadjust parallax at Shorter yardage. Maybe but I don't think so.
You see my dilemma.
All time records are, by definition, anomalous events. It would be unwise to make general judgments from them.
I checked with our friends at 6mmmBR. The records are recorded in inches. The 200yds. record, in inches, is divided by two for a direct comparison to the 100yd. The respondent could not answer definitively re. the 300yd agg. record but is probably done in the same manner. Those things being true, the dispersion is linear with slight increases for the increased exposure to environmentals. Appears we still have no evidence of smaller groups at increased distances.
I think I know the likely answer to this observation now � it�s in the second webpage link that I included in an earlier post. And from my experience it seem now to relate to sporter/service weight rifles that must be using ammo that has somewhat more liberal velocity variations.
It seems that a slower velocity projectile will leave the barrel as it points slightly higher due to recoil and the fact that a slower projectile stays longer in the barrel. On the opposite hand, a higher velocity bullet will leave the barrel as it points slightly lower. This means that faster projectiles will hit the target lower than a slower one (same weight projectile and at close distance). Don�t know how true this is � don�t recall what happens when I work up loads.
Further down the line, the trajectories will intersect as the slower bullet (initially shooting high) will drop down across and below the trajectory of the faster bullet (initially shooting low).
I did some calculations using JBMBallistics on-line software, and some assumptions, and it does show increasing accuracy (decreasing MOA figure) out to the trajectory cross-over (of course). I assumed a 144gn 308 with a velocity of 2800fps nominal and +/- 100fps variation. I�ll post an image of the trajectory chart later.
I did some calculations using JBMBallistics on-line software, and some assumptions, and it does show increasing accuracy (decreasing MOA figure) out to the trajectory cross-over (of course).
Plugging numbers into a program isn't real world data
Also, comparing trajectories and the POI of different weight bullets still has nothing to do with the claims that a particular gun with a particular load will shoot smaller groups as distance increases
I've never seen a ballistics program that could predict "accuracy" (as in group size, not POI) at all, since unless the numbers change, theoretically they should all hit the same spot.
No, it's the same bullet weight but at different velocities. The different trajectories and cross over could be misconstrued as varying accuracy, which I suppose it is really. After all, accuracy comes from consistency.
It's really easy to test in real life too - you don't need to shoot through the same targets at multiple ranges. Just need to load up to give different velocities (ie decrease the powder charge) and compare the POI at different ranges.
People don't factor in the effect of recoil on the angle of departure (me either - sounds counter-intuitive that it would result in trajectory crossover, given that slower projectiles are supposed to shoot higher at close range as a result).
I'm going to test this one day.
{Edit - Oops, I hadn't linked the correct article, here's the one I meant. Please read the second paragraph carefully:
I think I know the likely answer to this observation now � it�s in the second webpage link that I included in an earlier post. And from my experience it seem now to relate to sporter/service weight rifles that must be using ammo that has somewhat more liberal velocity variations.
It seems that a slower velocity projectile will leave the barrel as it points slightly higher due to recoil and the fact that a slower projectile stays longer in the barrel. On the opposite hand, a higher velocity bullet will leave the barrel as it points slightly lower. This means that faster projectiles will hit the target lower than a slower one (same weight projectile and at close distance). Don�t know how true this is � don�t recall what happens when I work up loads.
Further down the line, the trajectories will intersect as the slower bullet (initially shooting high) will drop down across and below the trajectory of the faster bullet (initially shooting low).
I did some calculations using JBMBallistics on-line software, and some assumptions, and it does show increasing accuracy (decreasing MOA figure) out to the trajectory cross-over (of course). I assumed a 144gn 308 with a velocity of 2800fps nominal and +/- 100fps variation. I�ll post an image of the trajectory chart later.
You have just successfully described the whole concept of using a tuner as is commonly applied in benchrest rimfire. Without the ability to tune the barrel harmonics, and control bullet exit timing of different velocity ammo, the match winning accuracy that displayed today wouldn't be possible.
It's really easy to test in real life too - you don't need to shoot through the same targets at multiple ranges. Just need to load up to give different velocities (ie decrease the powder charge) and compare the POI at different ranges.
The only real life test of the claims being made is for one of these folks to SHOOT that rifle at multiple distances with the same load on the same day with witnesses to verify the groups are consistantly smaller as range increases
All the calculations and load variations do NOT matter because it's not about "POI" of individual shots
It's only about group size, and no one will step up an take the test, even with a man offering to pay the expenses
The "compensation" effect in the link you posted, according to the author, only applied to the 303 Enfield, and not all rifles
Bear in mind, witness accounts are not entirely reliable. Speak to the police who have to interview witnesses after an accident or crime, and each witness's account will be different and conflict with the evidence from someone else. The trouble is that we interpret things and that affects what we "store" away in our memories.
The individual shots become the groups.
If no-one has come forward yet then I suspect that it is just a product of someones memory and interpretation ie not a reliable account.
Compensation for barrel flip applies to all firearms but the extent varies - it's physics.
From my experience/accounts/memories, I'm convinced that the velocity variation/recoil/vibration is the answer. It makes sense to me. I will test it myself one day but I'm not in a rush to do so - don't have the time or easy access to a long range.
The only real life test of the claims being made is for one of these folks to SHOOT that rifle at multiple distances with the same load on the same day with witnesses to verify the groups are consistantly smaller as range increases
Once again, each of those groups is an independent event. Such a trial, witnessed by 1 or 1 million, has absolutely no relevance to the posed hypothesis.
One must shoot a single string with every shot passing through targets spaced at a variety of distances. Each target will capture each shot. Then and only then can one claim that those groups describe a single event. He will have to show "dispersal" and then a subsequent "regrouping" as those slugs go down range. It's the ONLY way. I'd like a free trip, but don't have equipment that can do it.
Slugs dispersing from a common path at any point in their flight will never experience any sort of mid-flight correction capable of guiding them back to a common point. The processes depicted below cannot and will not ever happen.
Mauserand9mm: With some extremely serious science and velocity manipulations one can have vertical dispersion initiated at the launch point regroup as gravity and atmospheric effects expressed themselves. I.e. In BPCR a 45-70 shooter might use the upper path, and a 45-90 shooter the midline, and a 45-100 follow the lower with each launching slugs from a common rest for their muzzles. All arrive on target, but due to velocity differences follow separate paths. The paths depicted immediately above, however, would not be accurate renderings given that rates of fall would be more severe as we move downrange for the slower slugs. In practice though, we strive for a central aiming point and consistent velocity with our ammo. The central issue to the discussion here is mid-flight horizontal and vertical dispersal, followed by a regrouping in both axes. Just can't happen.
Too bad we can't get our boys in space to set up a range and eliminate atmospheric and gravity effects. It would be fun to "dial in" and test this at a range of several miles or so. Any budding astronauts out there or a shooter with connections to NASA?
I agree - but that would be only to prove if it were a spiral bullet path, which I now sincerely doubt. If it is a product of velocity variation/vibration then you don't have to shoot through multiple targets at different distances with the same project.
I'll post the graphs with explanation this evening when I get home (at work at the moment) - I hope this will better explain what I've found.
Once again, each of those groups is an independent event. Such a trial, witnessed by 1 or 1 million, has absolutely no relevance to the posed hypothesis.
I think it could help if results were consistant, and the farthest groups actually were smaller
The multiple targets could accomplish the task with fewer shots fired, but I imagine the shooters whose claim was disproved would then say the results were flawed because of the extra targets
But, as I said in the beginning, no one is going to take the test
Okay, this explanation satisfies my experience and what I have heard from others about increasing accuracy.
On the graph below, the green line is the trajectory for a nominal load (in this case a 308 144gn at 2800fps). The blue line is the trajectory of a 2700fps round assuming this variation with the ammo being used. The lower velocity means the bullet stays in the barrel longer and exits at a higher angle, due to recoil and muzzle flip.
The red line is a round at 2900fps once again assuming this variation (+/-100fps) with the ammo being used. It exits the barrel earlier and hence lower (less exposure to muzzle flip from recoil).
You can see that the trajectories intersect at around 325yds, so the MOA would be less here than at 100 or even 200yards - it looks like the accuracy is increasing.
Of course this assumes no accuracy error at all ie the group size is dependant on the difference in point of impact dispersion only.
I modified the chart to add a range of accuracy (1MOA - consistent across all ranges) to each trajectory, and have calculated and added measured group sizes at each range in inches and MOA. You can see MOA increasing towards 325yds then start dropping off afterwards, as the trajectories start spreading further away from each other.
Bear in mind, witness accounts are not entirely reliable. Speak to the police who have to interview witnesses after an accident or crime, and each witness's account will be different and conflict with the evidence from someone else. The trouble is that we interpret things and that affects what we "store" away in our memories.
I don't know why you would think that scenario has even a remote resemblence to several people watching someone shoot, and then verifying the results by viewing the targets
You can see that the trajectories intersect at around 325yds, so the MOA would be less here than at 100 or even 200yards - it looks like the accuracy is increasing.
The trajectories intersect because you're using a 325 yard zero in your ballistics calculator, and the calculation adjusts angle of departure to line up with that zero, regardless of the velocity or other parameters.
Try the same thing but use a near zero (like 50 yards) instead of the far zero, the results will be quite different, and more accurate (although still not perfect).
Yes, I believe in the cases I've heard about, velocity spread was likely (ex-military ammo or ready rolled of less than best consistency). The article I posted mentions it.
We don't have expert witnesses otherwise this issue would have been solved some time ago. I believe we have people making assumptions based on observations, myself included. Human nature to fill in the blanks of understanding.
Yondering,
The base load of 2800fps is zeroed at 100yards. I adjusted the departure angle to give +/- half an inch at 100yards (overall "group" or dispersion of 1MOA) for the 2700 and 2900 loads. They don't all exactly intersect at 325yards - I was suprised how close they came with my rough assumptions and calcs (one intersection at 310yds, another at 340yds and the last at 370yds):
We don't have expert witnesses otherwise this issue would have been solved some time ago.
I believe we have people making assumptions based on observations, myself included.
Human nature to fill in the blanks of understanding.
We dont need "expert witnesses"
All we need is for one or more of those who say they own these "magic rifles" to fire them with witnesses that can say they saw them fire smaller groups at long range than the gun could fire at close range.
Then they can let someone else run the same test with the same rifle to make sure it wasn't flawed
This doesn't require a lot of calculations and charts
It requires simple proof by doing it in front of a crowd
And yet not one has taken the opportunity to prove it to the world
I believe the velocity difference is what is causing the increase in MOA accuracy (but only at a specific range and then MOA accuracy increases again as the range increases).
And I'm actually with you on this, if someone says they use consistent loads and experience an increase in MOA accuracy at any range, then I really doubt this is true, and, like you said, they'll never be able to prove it.
Compensating barrel vibrations will only increase accuracy, with the normal drop-off as the range increases. The key is you need velocity variation to cause the trajectories to cross over and get the reducing MOA accuracy effect (but only at a specific distance).
It was an interesting myth to explore, but it's gone the way of bigfoot and the Loch Ness monster. Technology and science always kill off the unusual.
Edit: And I should add to those that claim to have witnessed consistent increasing MOA, I'm not calling you liers, just misinterpreting the observations. Like I've tried to imply earlier, if we are not prepared, we are poor witnesses. Nothing shameful about that.
The base load of 2800fps is zeroed at 100yards. I adjusted the departure angle to give +/- half an inch at 100yards (overall "group" or dispersion of 1MOA) for the 2700 and 2900 loads. They don't all exactly intersect at 325yards - I was suprised how close they came with my rough assumptions and calcs (one intersection at 310yds, another at 340yds and the last at 370yds):
If you include the [IMG/] codes in your image links, the pictures show up without having to click a link. (That's what I did in my post above with your link.) Photobucket does that for you if you use the IMG link.
I was reading about it last night.![[Linked Image]](http://s379.photobucket.com/user/rcamuglia/media/59ACBAEF-BF59-450F-97F4-A8DC17745081.png.html)
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