Thread: Brass too short
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Old April 14, 2013, 09:04 AM   #14
Bart B.
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Join Date: February 15, 2009
Posts: 8,927
There's no significant difference in neck tension across many thousandths difference in case neck lengths. For example, a .308 Win. case has a neck length spread tolerance of .020" as far as SAAMI specs go. The neck's about .300" long. Which means there'll be a but less than a 7% spread in case neck tension across a .020" neck length spread. Neck tension will vary exactly that much across a batch of cases whose length has that much spread if all things about the case neck and bullet jacket friction issues are exactly the same. There's no way neck tension could be held to that low of tolerance even with all cases exactly the same length and neck walls exactly the same thickness.

So, that much spread in case or neck length is not worth loosing sleep over. The most accurate ammo ever made will easily have a 10 percent spread in bullet release force or neck tension. I've measured ammo with a 20% spread in neck tension that produced 1/2 MOA accuracy at long range.

Last edited by Bart B.; April 14, 2013 at 09:11 AM.
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