Bullet Stabilizes at range but not close...why?

skipglo

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Set up a target at 200 and 300, shoot through the first target into the second, you will then be comparing the same 10 shots at 2 distances.
And can you explain how you are going to find a site that level in North America and other than a transit and shims how can you visually compare land deviation? I'm just asking here. Maybe I can learn something. Thanks
 

Pro2A

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Check your seat belt and cover your popcorn....it's gonna be an E ticket ride....... This phenomenon does not occur in true BALLISTIC CONTEXT per Bryan Litz as presented in his Applied Ballistics Seminar.......CUE THE PEEPS IN THE PEANUT GALLERY TO GO WILD!!!!!! All info is credited to Bryan Litz, Applied Ballistics,.....questions [email protected]. I am not stealing, plagiarizing (aka "Bidening"), just sharing what my $650 and 1350 mile (one way) one week road trip temporarily tried to teach this old guy. This perceived phenomenon is GROUP CONVERGENCE......when the group doesn't disperse in a natural linear fashion........the group MOA appears to get smaller at increased distance. One theory for group convergence is the "bullet going to sleep." Yaw vs Pitch relation dampens from barrel to down range becoming apparently more stable flight. Effects are self dampening resulting in very little steering effect......only about 1/10 caliber. POSITIVE COMPENSATION, possible only in the vertical plane, is another popular theory where higher velocity shots exit the muzzle pointed lower; slower shots exit pointed higher. Groups tend to be larger at short range - 100yds, converging at longer ranges - 600yds This occurs more often with less rigid barrels/action; less with stiffer/bull barrels.

Issues with studying convergence via live fire is need to screen same group at multiple ranges to directly observe convergence.....hence, the shoot-thru target tests. His extensive testing experience confirms zero effect of paper punching on ballistics. (I refer you to his address above.) Bryan presented numerous sleep inducing pages of data involving marginal/low stability, switch barrel caliber variation, aim point size versus distance to target, various combinations ad nausea, measuring and plotting Convergence Ratios that only a real Rocket Engineer (that he was before Applied Ballistics life) could or would want to understand.

Conclusions: The average convergence ratio for all testing was 1.16. There was no rifle/bullet combination consistently producing a CR under 1.0. He could not identify any direct physical evidence anywhere that convergence occurs demonstrably, repeatedly with center fire rifles, outside the previously mentioned mechanisms.....positive compensation, yaw/pitch. Even low stability cases exhibiting poor groups showed CR about 1.0.

Bottom line, the strongest connection between distance and angular group size was found to be related to the size of the aim point, making perceived convergence an optical, or psychological issue rather than a ballistic characteristic.

Bryan summarized that the belief in convergence has prevented the trust in load development at 100yds. But, the importance of understanding aiming is important. Summarized as Aim Small; Miss Small., or a parallax effect.

You may open those pop corn boxes at will. Class dismissed. Let the flaming and self-pontification commence.
 
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GLTaylor

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Well done Pro2A. Contrary to your opinion you obviously absorbed a lot of information.
I've never had groups get smaller at distance, but i SURE have seen them open up!
 

david g ranes

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I’m going to tell you a simple fix I sprinkle NyQuil Z on every box of bullets puts them to sleep before I ever load them it’s a secret though don’t tell anyone
 

hunter0528

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I second that. I'm no rocket scientist but the wind blows where I shoot and conditions change. It's environmentals.
And the wind can blow different directions and speed at different ranges. Ever seen the flags a Camp Perry and the 1000 yard range?
 

Dr. Vette

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This is the thread being referenced by a couple of other posts in this thread regarding the Shoot Thru Challenge:

 

Pro2A

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Pro2A: I am totally baffled by your bulls**t. (Or Bryan Litz's)
Tulsa Reiner.....aw, it's all in the wrist.....my stock in trade as The Baffleist. Made me a big boat load of wampum over 50+ years. Comforting to see I've still got it. :) :) :) The wind separates the shooters from the trigger tuggers. The BS separates them that has it from them that doesn't has it. :) :) :)
 

Pro2A

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This is the thread being referenced by a couple of other posts in this thread regarding the Shoot Thru Challenge:

Thanks, Dr. Vette. Litz noted that no one accepted the challenge. I forgot to mention that. Thanks for the update.
 

bpcrshooter

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set up 2 targets 9.4in apart (your rifle twist) and shoot at it. you should be able to see if your bullet is not flying right. look at the mark it leaves around the hole. The mark should be equal all the way around on both targets. You can set one in between at 4.7in as well.
 

LDHunter

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So here is the question: Why could I have a bullet shoot sub quarter MOA at 100yds then grow to 1 MOA at 200yds and then shrink back down to .5MOA at 300yds and 500yds. Rifle is a quality custom build in 300 WM and using Accubond bullets. SD and ES are single digit and I think I’m happy with the performance but never seen this personally. All the groups were 10 shots each so I feel pretty confident this is not a fluke.

Bullet weight is 200gr, velocity is 2900fps, twist is 1/9.4.

Thanks
Although I can't shoot as well as you, I have had similar results at varying distances and after careful analysis determined that I can't explain this phenomenon nor am I interested in the reason/reasons behind it. Analyzing something like this will leave you bat crazy and no good will ever come of it. I'm just very happy to shoot sub moa out to 500 yards on a good relatively wind free day.

The wind is NOT my friend nor do I attempt to explain just how and why it does all that crazy stuff to my groups. I also don't pretend to understand the effect of bullet spin and whether or not bullets go to sleep. If some of the greatest brains in shooting can't explain it and agree on the whats and whys of it all then I pledge to never lose one minute of sleep over it myself.

Carry on and focus on keeping your rifle and bullets shooting the crazy small groups you have them shooting now and you'll certainly find yourself rubbing elbows with other truly competent rifleman......
 

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