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Old June 8, 2019, 09:30 AM   #51
Bart B.
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JohnKSa, nice explanation in your post #48.
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Old June 8, 2019, 09:32 AM   #52
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Thanks guys.
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Old June 9, 2019, 02:29 AM   #53
Roadkill2228
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As far as wind affecting things more if encountered in the first third than the last, yes the bullet spends more time getting pushed around in the last but a plain English way of saying this is that if it gets off to a bad start it affects the whole trip.

Even in the absence of wind groups often open up more rapidly than what a purely linear relationship between group size and distance would suggest (meaning lots of guns and loads can do half inch groups at 100 that wouldn’t even come close to doing 5 inches at 1000). One thing that really contributes to this might be imperfections in jacket thickness and bullet concentricity. At close range these don’t matter all that much (visibly deformed soft points shoot lights out to 200 - 300 yards in my 243) but over distance and thousands of rotations it shows. Think of a washing machine that for whatever reason ends up loaded heavier on one side. At first you can’t tell, but as the cycle continues and it spins more and more it gets shaky and clunky and loud and sometimes even moves around where it isn’t intended to be. Laundry ballistics. This lines up with real life observations a heck of a lot more than the theory about spiral shaped trajectories and what is statistically observed on targets with many shots fired.
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Old June 9, 2019, 05:16 AM   #54
Bart B.
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Quote:
Originally Posted by Roadkill2228 View Post
Think of a washing machine that for whatever reason ends up loaded heavier on one side. At first you can’t tell, but as the cycle continues and it spins more and more it gets shaky and clunky and loud and sometimes even moves around where it isn’t intended to be. Laundry ballistics.
The laundry center of mass moves around in its shape.

The bullet center of mass is fixed in place.
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Old June 21, 2019, 01:05 PM   #55
Roadkill2228
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I must be missing something then. Wouldn’t it be the case that if
The bullet is not perfectly concentric/uniform then its center of mass wouldn’t be perfectly, well, centred?
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Old June 21, 2019, 01:40 PM   #56
Bart B.
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Quote:
Originally Posted by Roadkill2228 View Post
I must be missing something then. Wouldn’t it be the case that if The bullet is not perfectly concentric/uniform then its center of mass wouldn’t be perfectly, well, centred?
Yes. Very few of a given lot are perfect in that regard. Which is why 100 yard benchrest 5-shot group records are well under 1/10th inch but several groups average for aggregate records is much larger with the biggest group near 3 times larger. All the hundreds of other groups average bigger.

Some have spun bullets several thousand rpm checking balance. Perfect ones shoot most accurate.

Last edited by Bart B.; June 21, 2019 at 01:52 PM.
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Old June 21, 2019, 02:46 PM   #57
Jim Watson
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I used to read about the Vern Juenke Machine that provided a worthwhile sort on bullet uniformity. His son plans to make more.
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