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...
