While waiting for the definitive word from Germany, I will pose this question to the forum:
I have a pre-War Greifelt drilling in 16/60/16/60/7X57R. New England Custom Guns decided that the barrel walls are too thin to allow for rechambering to 16/70. I have some Brenneke rifled slug shells for another drilling, and although they are marked 70mm, in fact they measure 59.5mm. The difference presumably is a result of the 10mm of plastic case turned down over the Brenneke projectile, which presumably opens the length of the fired case to 70mm.
My question is twofold:
(1) Is it safe to fire the cartridges in my drilling in their present condition?
(2) What if I were to cut off the very end of the unfired cartridge, creating a situation where the turn down would now be an unattached sleeve, which presumably would be forced out the muzzle by the projectile?
I assume the purpose of this fold is to keep the projectile in place while subjected to the recoil force created by the other barrel firing, but how necessary is this?
The obvious answer to these questions could be obtained experimentally I'm sure, but the price and scarcity of pre-War drillings and Brennese ammunition being what they are, I would just as soon have an authoritative answer from a respected source,
