This has happened to me twice now. Shooting prone in the field with a bipod I have shot close to a one inch 5 shot string at 300 yards.
But I have never done any super tiny groups at 100. Do I have my paralax adjustment screwed up??? I usually forget to tinker with it. Its a loopy 3.5x10 M1
A friend of mine swears up and down that his other friend has a particular rifle that does not stabalize boolits until they are past 250 or so... to which I cried baloney!
Dixie, Sierra is in Missouri too! I read about this in a Sierra loading manual. They call it "Gyroscopic Precession". They claim it is similar to somone throwing a football. Long skinny bullets are affected by this more than short fat ones.
I like to do my hunting BEFORE I pull the trigger! There is only one kind of dead, but there are many different kinds of wounded.
Man you got me laughing so hard! Next time I am at the range I am gonna pull that one out and throw it on my bud... Gyrscopic Precession! Dang! between that and metplat and coriollis how do we ever git on paper???? LOL
BTW when the chrono says perfect and the paper says no, I personally think you have the load balanced but not in the sweet spot of the barrel, such that if you keep the low es and sd, and bobbed the barrel half in inch at a time you'd find you would get into the sweet spot AND have the best of the chrono...
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
My 1K BR rifle has shot a best of 5/8" at 100 yds. It's best 1000 yd group is 3.5," and it has shot several 4" or better. It's not uncommon at all for long, high BC bullets to moa better at longer ranges.
Yet lots of folks will happily call 3 of us liers...
Who cares? That old Bull Rifle was designed for long range, and I've even had guest shooters get the same result with bullets as light as 168 grain Sierra Match. Results is results, right?
I attribute it soley to parallax. Someone with lots of coin will have to set up some optical screen targets in a series and pass each round through the series to make a believer out of me. In other words, show me the numbers, and the numbers must come from the same 10 rds measured at each range. Putting 10 rds thru a paper target at 100 yds, and then another 10 rds at 500 are two completely independent and unrelated events. If one has garbage at any point along the path, he will have garbage for the rest of the journey. There are no ion trails out there that will cause one's bullets to converge as they move further down range.
Another potential aspect is having targets that fit ones sights at each range. I.e. at 100 yds the bulls eye will be 1/4 inch when using my 257 with its 24X scope. Move to 400 and a 1 inch bull will fit the cross hairs almost perfectly. Consistently shooting small at each range will typically improve ones performance. 1Minute
It can be parallax except those like Blaine and myself shoot up to 10K rounds a year and know how to take that out... Its not in our case, related to the scope...
Its simply the bullet not going totally to sleep. Very common with high BC bullets.
It has nothing to do with target size either, my targets are made for whatever I'm shooting, IE 300 is different than my 600 yard targets, I actually make them each time I shoot after I see what power of the scope I can see best with that day due to mirage issues unless I'm shooting at night.
Of course if you shoot diamonds, target size isn't as critical.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
rost, how important is velocity with putting the bullet to sleep? I am working on a load with 115g Berger VLDs(.257) and I am not getting the groups that I want to get at 300 yards for a varmint target shoot. (Shoots really well at 100y) Should I speed it up or slow it down? Will that matter?
I am going to shoot the same load at 600y and see how it shoots.
Lastly if you are working up a load for a particular distance, do you shoot off a bench at that distance or do you load develop at 100 yards?
Do you shoot a load at different distances to see when it goes to sleep?
Velocity only matters a lot if the twist is wrong. Stabilization becomes a problem with sleeker bullets, longer means sleaker and that means faster twists required OR running the bullet faster, which can tear the jacket apart. Shot some 64 bergers in a 7 twist once, pushed too fast and too fast of a twist, not a one ever hit paper. So there are both sides.
If I was going to run a specific bullet I always twist up for that bullet per the formulas for twist. Then I can feel safe working in the parameters of the cartridges speed without pushing safety.
How do I work up a load. I shoot the bullet I want to shoot, at the distance I want to use it at. I haven't shot more than deer rifles to test zero's at 100 yards in years. My testing all starts at 200 or 300 yards and extends out. The first thing I do is run an audette test preferably at 300 yards. Take the fastest clump and load them up in groups of 3 or 5, shoot them at 300 to reverify, then take it straight to 600. 600 can show errors better, IE I play with neck tension, seating depth and primers at full distance. Thats IF what I take to 600 doesn't make me happy.
You also may have issues with case weights, non concentric issues and so on, that generally don't show at 100.
In fact the only reason I found that some loads didn't work at all at 300 but did at 600 was a fluke, I shoot different loads, 300 I shoot a cheaper load/bullet. But one day I was shooting a 300 yard match and it was really quick switching winds, I thoughth, heck I'll run my 600 ammo and have an advantage... not at all really, it barely would hold the 10 ring....Went out and shot it scoped at home, same thing showed.. I've also got a kick butt 300 prone load, that doesn't fair well at 600, but at 300 I've shot 5 shot groups of an inch...
Good luck, Jeff
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Never been to Missouri, but the physics of what I'm reading is mind boggling. Can't even begin to imagine how one might model this phenomenon. As I understand it, bullets leave the barrel at 2 moa and then turn 1 moa to group 1 moa? I'm a lot more comfortable with paralax. There was a lot of people that saw the edge of a flat planet, also. I am sure that you are seeing the results that you are reporting, just not buying the explanation.
Last edited by mcmurphrjk; 03/09/08.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
Hadn't heard about this "gyroscopic precession" before. Will have to look this up later.
Have found that the 160 gr GameKings and AccuBonds do pretty good @ 100 yards (.7" and .75") in my custom Sako 7MM STW hunting rifle, but do very well further out; 3" @ 400 yards and 1.6" @ 300 yards, respectively (when I do my part!). This didn't add up to what I'd read or been told before. (1" @ 100 = 2" @ 200 = 4" @ 300 = 8" @ 400) The only random guess I've received of late was a question about the muzzle's crown.
Blkram, a minute of angle (moa) is a unit of angular measurement, 1/60 of 1 degree. Calculating the physical equivalent group size equal to one minute of angle can be done using the equation: equivalent group size = tan(MOA ∕ 60)*distance. In the example previously given and substituting 3600 inches for 100 yards, tan(1 MOA ∕ 60)∙ 3600 inches = 1.0471975511966 inches. As a linear equation, 1 moa (or 1" for simplicity)at 100 yds would be 3.15" at 300 yds, and approx. 4.2" at 400 yds, etc.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
mcmurph, how do you argue the point that if you are in the center of your scope, there is no parallax?
Cant say I quite understand the gyroscopic precession model myself either, but that is more than has been offered so far.
How do you explain that 115g NBT out of my .25-06 will shoot .6s at 100 yards but will shoot .4s and .5s at 300 yards? I would attribute it to luck myself if I had not repeated this drill multiple times. Last time I went to the range, I shot 4 5 shot groups(clean barrel after 2 fouling) at 100y than went out to 300y after cleaning again and 2 foulers, repeated the 4 5 shot groups and the 300 yard groups were smaller on average.
kyreloader; My first instinct for an explanation is that it is a paralax issue, but I am perfectly willing to accept that it is properly adjusted. I am perfectly willing to accept your group results. What I am unable to accept is the explanation for the phenomenon. I cannot believe that a bullet can accurately and reliably turn an angle at some point in its flight. As for Gyroscopic precession, it is about a gyroscope with a gimbal returning to it's natural axis after a disruption or initial instability. My issue with this explanation is that a bullet has no gimbal. Precession explains a bullet becoming stable, but does not explain it turning an angle in order to converge at an aiming point. http://en.wikipedia.org/wiki/Gyroscopic_precession#Torque-induced_precession
All this is to say that I believe the experience of the posters, I just don't know the explanation.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
I agree whole heartedly. I am having alot of trouble understanding the discussion as well. I cannot understand how a bullet "goes to sleep".
I hope someone smarter than me can explain this to me and make me understand. I am willing to accept any readings available on the subject if anyone has any good links.
kyreloader, Gyroscopic precession perfectly explains how a bullet "goes to sleep", or more simply becomes stable. What it doesn't explain is how bullets turn and re-converge on a target.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
The very BEST thing to do here, is quit WASTING time reading crap that won't make you a better shot, accept the paper results and keep on shooting! IMHO, Jeff
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Tonight is the first time that I have noticed this thread, but not the first time I have been in a discussion on this topic, what rost495 and Blaine are talking about really does exist. I have seen it several times myself. I have never heard it refered to as "gyroscopic precession". I have always known or refered to it as "Yaw" or more specificaly "the yaw of repose". I am not going to get in a debate with non-believers on this topic, if you dont believe go and buy a very fine book by Robert Rinker called "Understanding firearm ballistics". Robert has a chapter in this book that explains this topic very well. B
boatanchor, I am sure that an under stabilized projectile can become stable down range, and physics explains this. I am also sure that the better grouping my fellow posters are describing is also real. My point is that if the groups are tightening up, after dispersing due to this yaw, physics demands a better explanation.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
I have Rinker's book and dragged it out. The chapter describing "yaw" and "nutation" doesn't say that the bullet's path returns to some true path downrange. (Chapter 8 right?)
I have had this discussion with Jeff several times now, and don't doubt his observations. Another good book to read on this is Rifle Accuracy Facts, by Harold Vaughn. Dr Vaughn's says "poor statistics". I try to keep a more open mind on the matter.
If you have Franklin Mann's book, "The Bullet's Flight...", he first describes this spiral path, ingeniously documents it, then sets out to try to understand and explain it. He shows that the bullet does take a spiral path, but the center of the spiral is random once it leaves the muzzle.
I too would like a better explaination of the phenomenon.
I've never seen a group actually really tighten up, but I have seen the dispersion of the group basically stop for a while at mid range. IE same size group or just a bit bigger at 600 compared to 300 yards.....
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Coincidentally, there's a parallel discussion going on in the NationalMatch forum. Here's about the most cogent and detailed analysis I've seen to date; http://bryanlitz.bravehost.com/EpSwerv.html
I had the opportunity to pose the question about grouping smaller at longer range to distinguished Ballistic engineer, William C Davis Jr, of Tioga Engineering. He just wrapped up an incredible career doing work for outfits like Aberdeen with sidelines as a technical editor for American Rifleman. He's also the designer of the VLD bullet (Very Low Drag). In our conversation, he essentially asserted what Brian Litz says in his article. The "corkscrew" path is actually quite small (he introduced me to the terminology "swerve", and in all his work, had never seen the phenomenon in a controlled test.
What impressed me was that he didn't flat out reject the existence of the phenomenon, but just said he hadn't ever seen a well documented case of it. During the course of our conversation, he proceeded to think out how he would conduct an experiment to document the phenomenon using thin paper targets at various yard lines. Others since have extended that line of thinking proposing acoustic targets to further prevent disturbing the flight of the bullet, yet documenting the groupings at the various yard lines.
Democracy is not freedom. Democracy is two wolves and a lamb voting on what to eat for lunch. Freedom comes from the recognition of certain rights which may not be taken, not even by a 99% vote. *Marvin Simkin* L.A. Times (1992)
I've never seen a group actually really tighten up, but I have seen the dispersion of the group basically stop for a while at mid range. IE same size group or just a bit bigger at 600 compared to 300 yards.....
I think this is the best communicated explanation. To me it says the rate of dispersion is descreasing slower than the increase in range. The bullet isn't turning back just dispersing at a slower rate than in the beginning of its flight due to it becoming more stable. Does the same phenomenom occur with arrows? Seems that it should on a smaller scale. Just some thoughts.
I got into a similar discussion over on www.longrangehunting.com and let me tell you, some of those guys are using higher math than me! The simplest explanation I received is that the bullet spins around it's center of form in the barrel, then transitions to spinning around it's center of gravity after it exits the barrel. These two points are always a little different due to the inexact science of bullet construction. The longer the bullet, the longer it takes to make the transition. During this transition period, the bullet is not stable and bullet paths are somewhat divergent. After stabilization occurs, the bullet path "straightens out", and the bullet paths are much less divergent. The bullets do not curve back towards the center point, but they do not have to in order to have smaller MOA groups at longer distance. If we were talking strictly inches and not MOA, group sizes do continue to grow as distance increases. Sometimes not much after stabilization occurs, but they do get bigger. I did have a guy claim that he saw a heavy barrel rifle that would shoot 3 inch groups at 100 yds but at 300 yds the groups were only 1 inch (yes inches, not MOA). I stopped short of calling him a liar but said that there was no way I would believe that unless I saw it--my diplomatic way of calling him an idiot. I hope this explanation contributes usefully to this topic. I'm not an expert on exterior ballistics but it made sense when explained to me.
Never been to Missouri, but the physics of what I'm reading is mind boggling. Can't even begin to imagine how one might model this phenomenon. As I understand it, bullets leave the barrel at 2 moa and then turn 1 moa to group 1 moa? I'm a lot more comfortable with paralax. There was a lot of people that saw the edge of a flat planet, also. I am sure that you are seeing the results that you are reporting, just not buying the explanation.
I haven't read through all the posts...I didn't need to. A bullet leaves the barrel...If it is spinning fast enough it will have little if no "YAW" so to speak..."same as a top that has been released from the string"...at first it will have large lopeing loops until it settles down into its "groove"...I'm not sure of the "physics" part but I've seen enough tracer rounds sent downrange to know that it can be seen...stable bullets will be pencil thin, whereas unstable bullets will have a "larger" looking glow..."SAWS" & fully auto weapons will have a larger heat signature than a comparable caliber in a low volume fire weapon...I imagine because the barrel heats up pretty quick & it takes a little bit of time for the bullet to "settle"...When first fired...full auto weapons will have a somewhat smaller signature than they will after a few hundred rounds are fired...As far as paralax is concerned...I have NEVER seen paralax as being an issue at 100 yds. then magically disappearing at two...It just doesn't work that way...
When I set as closely as possible the parallax setting on my scopes for 300 yds., I'll get groups from .87-1.5 inches with my rifles. But at the same parallax settings, I no longer get any groups much under .6-.7 @ 100 yds. But if I set the scope to be as parallax free as possible for 100 yds., I do get groups down into the .3-.5 inch areas. It's all well and good to talk about placing your head directly behind the scope to eliminate parallax. I, for one, have never been able to achieve that. E
Yes, I'd say you have a parallax issue. I even dial it out when shooting ground squirrels with the lowly 22 LR. For young squirrels that are only 1/2 inch wide and a variety of shooting postions, it can have a signigicant effect when ranges vary from 5 to 150 yards or so.
I will not put a scope on any rifle that I expect to reach out that does not have some means of correcting the problem.
I just thought of a way one might weakly test this with a scope that does not have any parallax adjustments. Just hit paper at one range while actually sighting at a second. Lets say a given unit is parallax free at 300.
1) Take that unit and zero poi to be about 2 feet low at 300 yards.
2) This step will take some help... Place a target at 100 yards and a second at 300 that is postioned such that the 300 yd bull appears to sit precisely on the top edge of the 100 yard paper.
3) Fire 5 rounds while sighting on the 300 yrd bull. Since those rds are running low, they will punch the 100 yard paper while one is actually using a 300 yard sight picture.
If the unit is indeed a 300 yard nail driver, my bet is the 100 yard group will likely be a one holer too.
The reverse could also be attempted by running poi high with the same unit, sighting at 100 yds, and actually hitting paper at 300. If the unit has habitually opened up at 100, I bet it will really open at 300 while using the 100 sight picture. Something to do when we truly have too much time on our hands.
Still, optical or audio screens that have no physical effect on trajectory would be the primo test, but that would require more coins and equipment than I have available.
How much are the audio screens? Im kind of suprised a manufacture or someone with the necessary coin has not put this to rest with some quanatative results just to get their name attached to it.
Hunt hard, kill clean, waste nothing and offer no apologies.
"In rifle work, group size is of some interest...but it is well to remember that a rifleman does not shoot groups, he shoots shots." Jeff Cooper
To be honest, I don't know, because I don't move in those circles. My exposure is limited to conversations with some shooters that are just on the verge of moving into Olympic level competition. They have trained and competed in the Colorado Springs facilites where literally every aspect of ones actions can be recorded and played back. They have the ability to continuously monitor sight picture, heart beat, eye movements, etc, and link those with the nanosecond that trigger pull occurrs and the pill leaves the muzzle. One of my frustrations that I've not worked on but am aware of is a need to work within the tectonics of my heartbeat. I suspect I could halve group size with some training in that area alone.
Acoustic units are used around here in Oregon for some local/regional indoor stuff. Given the accuracy demands of competition scoring and the small targets, they must be quite dependable and precise. I think they use impact sound on a physical target though, detected by 3 or 4 mics, to triangulate shot placement. Thus, one does not have uninterrupted flight with an acoustic system. Their real plus was that scores of the whole line can be updated as shooters progress through their shots.
From a little surfing, I believe the next generation units are employing photo-electric or lazer scanner techniques that can monitor bullet flight at several ranges without affecting trajectory. To date though, I think they have only been used to track a single POI much like the acoustic units. With that kind of setup, the argument could eventually be put to rest though. Maybe I can take it on after retirement with my yet to be acquired lottery winnings.
A more costly issue might be the 500+ yards of extension cord needed to set up the computers and targets at distant ranges. Have a good one. 1Minute
There are acoustic targets somewhat within the means of hobbiests. Ken Oehler, who posts on this board in the "Ask the Gunwriter" sub board produces one that I believe is an option to his PBL package. As 1minute has mentioned, they use mic's to triagulate the passage of the bullet. Where it differ's from 1minute's account is that the shock wave is picked up by the mics and paper is not necessary.
I had a conversation with a noted Ballistic Engineer a few years back, and he proposed using very thin paper on the midrange target (ie onion skin etc) that would not disturb the flight of the bullet as it travelled to the terminal target. It's arguable whether that midrange target would appreciably alter the natural flight of the bullet. I'll have to go back and re-read Dr Franklin Mann's book too.
I don't claim to be an expert long range shooter but I have observed the same thing as well. Not uncommon for a rifle to shoot 1 1/4" at 100 and shoot 1 3/4" at 200. I have done it a lot.
I have coached high school football for nearly 30 years and have seen the same thing happen to footballs when passed or punted. They will sometimes start off with a wobble then stabalize half way to the receiver or returner. You can't see bullet in flight but I can see a football.
Most people don't really want the truth.
They just want constant reassurance that what they believe is the truth.
I have little doubt that slugs can start out with some degres of instability. What I do not believe is that they can stabilize and then miraculously converge to a tighter and more precise track than they started with. In any application I've ever worked with, if it's garbage to start with, its garbage at the end.
I am not a ballistician...heck I aint even very smart but I have seen the smaller MOA groups at longer ranges several times. I have an extreme example with my 30/06 AI shooting 208gr A-Maxs. My groups at 100 are unsuitable barely MOA. However at 800 yards it has posted some groups well under 1/2 MOA. The only way I can figure it is to envision a line that is the intended path of a bullet, then envision a path orbiting or rotating around the intended path in decreasing orbits. I cant explain the opposing forces acting upon the bullet to cause this. If the orbit around the intended path is basically a bullets width it will appear to be 3x the actual variance on paper.
EddyBo: My point exactly. We are describing two completely independent events here if we consider each group as an event. First the 100 yd group and then a subsequent and totally independent 800 yd group fired under different condtions. What we really need to do is follow that 100 yard spread out and make a second measure when those same slugs reach 800. Conversely, we should have measured your 0.5 moa 800 yarder at 100. I very very strongly suspect it was a "one holer."
I've done all kinds of unexplained things with independent events. I've shot three of four 2.5 moa groups at 100, been unhappy with things, come back after a brief walk, and punched out a 0.5 moa cluster with the same rifle, ammo, weather conditions, and sight settings. Had I moved the target out to 800 after the intial rounds, I would have thought it a miracle. Most likely that was the shooter, and I just needed to grit my teeth and settle down.
Any number of things can affect 2 events. Most of us put more effort, a better trigger squeeze, and more concentration into long range tasks. Sight pictures may be different depending on target size, some barrels need a few fouling shots to iron out, parallax will come into play at varied ranges unless one can dial it out, and wind can be a factor at one or more ranges and not others.
In an absolutley controlled environment (a long draft free tunnel), a group of slugs that have dispersed to a 1 moa spread at 100 can not subsequently reduce that rate of spread at any multiple of 100 yards. Once a pattern has been expressed, it will at least sustain itself. More than likely there will other unforseen variables and things will probablyy disperse at a faster rate than we anticipate.
A single pass target system at both ranges would eliminate input from most of those variables.
I've read all kinds of speculation on convergence, but never ever seen a single piece of evidence that it actually occurs. When that evidence is produced and published, I'll be quite willing to step forward for the first helping of crow. My challenge then will be to find a physists that can explain why or how it happened and exploit their findings. That work will result in a complete revision of our physics text books at all levels.
At to applications, I'll go out and design a shotgun choke that will be "improved" at 25 yds for quail and converge to a "full" at 50 for geese, make a killing off of new fire hose nozzles and more focused lasers, and think up a 100 other ideas in my sleep.
Maybe we should suggest this to the myth busters???? I'm not sure they have a budget and the expertise to take it on, but I think we could find a believer out there that would loan them a rifle and some ammo.
I'd offer mine, but I don't think my units exhibit that behavior.
Like I stated I cant prove anything and am just speculating but my groups are not a one day one occurance thing. The rifle has been shot by myself and others with the same results. Most of the others are better shots than myself and none have posted much better than MOA at 100 yards, some have posted much better than 1/2MOA at 800 yards. All of us know how to adjust parallex. I can only go by my experiances, but that is what appears to be happening to me. Here are some links to two threads from another site that has some people more knowledgeable than myself with similar thoughts on the matter. I think I also saw some similar threads over on BR central and 6mmbr also, most seem to take it as fact also. Good luck finding answers.
I know I've shot enough groups at 300 and 600 with my 223 and a 6.5 twist and 90 jlks, to know that I'm hard pressed to get a 3 inch group at 300 ever, usually over that.... and I'm hard pressed to ever shoot a group over 3 inches at 600...
I know thats not a shrinking group.... but it sure says some strange things that are repeatable.
I have shot enough groups that also do show smaller MOA the further out, but not repeatable enough to be reliable in my mind.
Jeff
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
I have traded off several rifles based on poor groups at 100 yards. Stupid! Long range is what matters, I now judge what the gun will do at long range. My 700 SS MT rifle is consistant 1.25"/100,1.5"/200and 1.75"/300 yards, there is a bit of windage at 100 as well...Another LR tip, if you are shooting a rimfire and cannot choose between brands or lots (by group size), try shooting at 200 yards... the more accurate load will be evident, (same applies to handgun loads, who cares about a half inch at 50 yards). Put up some long range targets, you will learn some things! Bill
Dixie, Sierra is in Missouri too! I read about this in a Sierra loading manual. They call it "Gyroscopic Precession". They claim it is similar to somone throwing a football. Long skinny bullets are affected by this more than short fat ones.
I like to do my hunting BEFORE I pull the trigger! There is only one kind of dead, but there are many different kinds of wounded.
Looks like Litz in Michigan is showing up the Missouran's in "Show Me". Gyroscopic Precession may be a real phenomenon, but that bullets can then converge on the true path is the question.
mcmurph, how do you argue the point that if you are in the center of your scope, there is no parallax?
Cant say I quite understand the gyroscopic precession model myself either, but that is more than has been offered so far.
How do you explain that 115g NBT out of my .25-06 will shoot .6s at 100 yards but will shoot .4s and .5s at 300 yards? I would attribute it to luck myself if I had not repeated this drill multiple times. Last time I went to the range, I shot 4 5 shot groups(clean barrel after 2 fouling) at 100y than went out to 300y after cleaning again and 2 foulers, repeated the 4 5 shot groups and the 300 yard groups were smaller on average.
Interesting observation, but the variability is established during the front end of the flight. Also, notice the term "simulation". Garbage in = garbage out. Slugs just don't come with steering wheels to put them back on track.
No one will. Anyone with a shred of critical thinking skills will know that a bullet can not change angles of flight by itself. I, of course, have seen rifles systems that shot better at LR than at shorter ranges, but in every single case we were able to trace it back to something else besides "going to sleep". This idea got a lot of traction in certain military circles a few years ago with ELR 50cals and 408 Cheytac's. Several consistently shot smaller groups at 7-900 yards than at 100 yards. Finally they were shot through acoustic screens at multiple ranges.... The groups were lineal... Who woulda guessed. The guns did in fact shoot better at distance, but it was always something else.
Unless you believe that certain bullets have magical properties, they can't auto correct. Even if the bullet isn't completely stable at first it is still "wobbling" around a cone, a cone from which the center is already divergent from the "bore line" a certain degree. Even when it "stabilizes" and the cone gets smaller, it still has the angular divergence that it started with.
Interesting observation, but the variability is established during the front end of the flight. Also, notice the term "simulation". Garbage in = garbage out. Slugs just don't come with steering wheels to put them back on track.
OneMinute, Here's something funny; That video was actually produced by Litz. Apparently it's not uncommon that folks misinterpret it. And in the LongRangeHunting thread, Litz provides the following clarification;
Quote
This video is often misunderstood. Note that the illustration on the left is not showing the path of the bullet, it's showing the angle that the nose is pointed. the view on the right is showing the bullet path from the shooters point of view. You can see how tiny the actual 'corkscrew' path of the bullet is.
This video is the result of modeling which means it's only as accurate as the inputs, and there are a lot of inputs needed to make a 6-DOF model work. I'm sure that there are some imperfections in some of the inputs. However, when you consider that the model would have to be wrong by more than 100 times in order to show the level of group convergence that's commonly claimed (1 MOA at 100 and 1/2 MOA at 200), it becomes far fetched to accept epicyclic swerve as the explanation.
Here's the 2.0 version of Litz' video that might make clearer what exactly it represents;
It's not uncommon at all for long, high BC bullets to moa better at longer ranges.
Right, exactly, when you're measuring angles, not absolute group size. I had a Sendero in 7mm STW that shot 3/4 inch groups at both 100 and 200 yards. It would also shoot 3/4 MOA groups, in other words, 4 inch groups, at 600 yards. There was some wonky wobble for a short distance downrange.
If someone is getting smaller groups, in inches, not angles, at longer distance, I'd suspect parallax or some other source of user-induced aiming error.
Tom
Anyone who thinks there's two sides to everything hasn't met a M�bius strip.
often I can get better groups at 200 and 300 yds ( if the rifle is up to it ), but that has been as I figured due to having depth perception issues, due to have a head injury playing baseball in college.....
spent two weeks in the Hospital, under sedation at Chelsea Naval Hospital in Boston, as they were concerned I was going to potentially lose my sight....
that didn't happen but I have had depth perception issues ever since, and the closer it is the moreso, but goes away as the distance increases...
don't know if this applies to anyone else, but just another possible explanation.... this happens with a batch of my rifles...so its me, not the rifle or ballistics...
Not to get into a pissing match but if you spin a gyroscope as fast as you can you will see it go to sleep shortly after starting it. Not too hard to extrapolate that to something spinning 180,000 rpms.
Not to get into a pissing match but if you spin a gyroscope as fast as you can you will see it go to sleep shortly after starting it. Not too hard to extrapolate that to something spinning 180,000 rpms.
We all agree on the behavior of a gyroscope or a spinning top. The question is, assuming similar precession/nautation action for a bullet, would the bullet actually fly in a way that allowed it to shoot smaller (MOA) groups at long range compared to short range?
There's a difference between rotational motion and trajectory/path. How much the precession/nautation translates into path deflection is calculated to be very small (like 1/10th of a caliber). And so far, all efforts to observe this effect with live fire have shown linear growth of groups with range.
If you can CONSISTENTLY shoot sub 1" groups at 300 yards, your load is where you want it. Watched a fella last month work up a load in a 308 and got it shooting where he could cover 10 shots with a penny at 300. He is now a long range high master at 1k yards. If it shoots at 300 it will shoot good at any distance.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. --Winston Churchill
I agree. At least all 34 posts are loaded with great info.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. --Winston Churchill
What's this guy shooting at a 1,000 yds using for a load. Need to use heavy bullets for a 1,000 yd shots. and is he a "real" shooter, ie: off the ground on his belly, with iron sights, or setting at a bench with a heavy rifle and 30X or something scope. All matches at Camp Perry (national matches) are fired at 600-1,000 from the prone, off your elbows, with iron sights. The only scope sighted match is the Wimbledon. And even there, the X ring is 10" and never been a clean on that (all in the X ring). Last time I looked, the record was 200x18Xs. I'm unaware of any High Master classification in BR shooting.
What's this guy shooting at a 1,000 yds using for a load. Need to use heavy bullets for a 1,000 yd shots. and is he a "real" shooter, ie: off the ground on his belly, with iron sights, or setting at a bench with a heavy rifle and 30X or something scope. All matches at Camp Perry (national matches) are fired at 600-1,000 from the prone, off your elbows, with iron sights. The only scope sighted match is the Wimbledon. And even there, the X ring is 10" and never been a clean on that (all in the X ring). Last time I looked, the record was 200x18Xs. I'm unaware of any High Master classification in BR shooting.
If he's using a .308(Win) he's most likely shooting F-TR. Scopes are allowed.
Could be. But F-class is essentially benchrest shooting from on the ground. Not saying it's easy, targets only 1/2 as big scoring rings size. I'm hoping to get to one down at Camp Butner this year. Not to shoot, as much as watch and see what's going on.
But F-class is essentially benchrest shooting from on the ground...
Shoot F-TR with a .308 at Butner and get back to me on that train of thought. Nice range, challenging winds.
I've shot with Ray Gross who is the captain of the U.S. National F-TR team. Ray is a distinguished prone sling shooter, watched his transition from sling to F-TR. There is a learning curve.
IIRC up until a few months ago there were only three Long Range High Masters in F-TR in the country, two of those made HM shooting F-Open.
Again, parallax or technique issues. While I like to think otherwise, my techniques gets additional consideration when I'm really trying to reach out.
Once slugs begin to diverge they will never ever subsequently converge even if there is a stability issue as they exit the muzzle. Then there are folks aound that still think the world is flat.
Can't remember who, but there is someone about that is willing to take on the sows ear turning into the silk purse down range. I've not heard of anyone having to pay up yet. To be proven, one needs a series of optical or acoustical targets down range to assess accuracy/precision across ranges for the same string. One can not compare separate strings fired at a different ranges as they are independent events.
Applied physics is for classes, applied shots at various distances will show what is really going on.
OceanBlue is 100 % right, my old bench rest target shooter friend said the same thing. my 257 Weatherby shoots 3/4 inch with just a little keyhole, but at 200 yards bullet holes are perfect and under 3/4 inch groups ,300 yards 1 inch or less. me and some other shooters figure because my 257 Weather mag. is shooting very fast it takes a little longer for the bullet to stabilize. Here`s a question about reloading most of the new reloading books have a few grains less powder maximum loads than the older books. yes I understand there are newer better ways to test pressures,but nobody who handloaded with the older reloading manuals ever had trouble if they followed the old manual maximums . so why then is it liability ? new rifles are not built as well " and it almost appears that way" ? I know my old Winchester model 70`s pre 64,old Sako`s and my Ruger no.1`s seem to handle maximum loads way better too,so I kinda feel the new rifles are just not as strongly built or barrel-reciever medal is not as hard ?
Applied physics is for classes, applied shots at various distances will show what is really going on.
OceanBlue is 100 % right, my old bench rest target shooter friend said the same thing. my 257 Weatherby shoots 3/4 inch with just a little keyhole, but at 200 yards bullet holes are perfect and under 3/4 inch groups ,300 yards 1 inch or less. me and some other shooters figure because my 257 Weather mag. is shooting very fast it takes a little longer for the bullet to stabilize. Here`s a question about reloading most of the new reloading books have a few grains less powder maximum loads than the older books. yes I understand there are newer better ways to test pressures,but nobody who handloaded with the older reloading manuals ever had trouble if they followed the old manual maximums . so why then is it liability ? new rifles are not built as well " and it almost appears that way" ? I know my old Winchester model 70`s pre 64,old Sako`s and my Ruger no.1`s seem to handle maximum loads way better too,so I kinda feel the new rifles are just not as strongly built or barrel-reciever medal is not as hard ?
My 1K BR rifle has shot a best of 5/8" at 100 yds. It's best 1000 yd group is 3.5," and it has shot several 4" or better. It's not uncommon at all for long, high BC bullets to moa better at longer ranges.
Except no one has ever proven that's true,
One shot, one kill........ It saves a lot of ammo!
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