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One of Us |
After twice fireing some cases that were resently made to fit the second 7.62 X 41 I found that they all had shortened between .010"to .015". In all my years of fireforming I never realized that this happens. Thinking about it, however, it is definitely understandable. Anyone else surprised? roger Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | ||
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Moderator |
well, i won't tell you that you ight have over shortned them when they were trimmed, first or most immediate time.. but if they are 41MM long BEFORE firing , and anything like improved from after, than of course they are now corret in all other dimensions... i trim the AR cases to 2.65 if i die form them, then fireform and trim to 2.55, for thr rumbased ones opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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One of Us |
Prior to loading and fire forming the cases measured nominally 1.618". They now measure between 1.604" to 1.615". Is it so hard to believe that the brass necks can donate to the forming of the body and shoulder? roger Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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one of us |
Anytime you sharpen a shoulder or expand it in diameter to reduce the taper of the cartridge body, the cartridge usually ends up being shortened as the brass has to come from somewhere. Even if it's just that the chamber is a little larger than the brass, that first firing will shorten the brass as it expands to fit the chamber more exactly. | |||
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One of Us |
I see it the same way, now, never gave it much thought before. I use to shoot trap in Grand Junction ,late 60s early 70s with a Dwayne McDermott. Any relation? roger Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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one of us |
I've observed this a couple of when forming 'cats. I do suscribe to the notion that as you "true up" or "blow out" the body/shoulder and shoulder/neck junctures, your case shortens. Think about it as a piece of string laid alond the surface, being fixed at the case head. As these curves straighten into crisp angle points, the path becomes longer, but not the OAL - it must shrink. | |||
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One of Us |
Nice analogy roger Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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