.45 ACP Case Length

[Bruce McAskill]

You have discovered what the military has know since the 1920's that the .45 acp is one of the very few cases that in reality shrinks each time it's used instead of getting longer. You never have to trim a .45 acp fired in a semi-auto. I don't know if that also is the case if fired in a revolver but would not be surprised if it also shrank in that too.

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[Gun Surfer]

"You have discovered what the military has know since the 1920's that the .45 acp is one of the very few cases that in reality shrinks each time it's used instead of getting longer."

Actually, in measuring cases I have observed shrinking for some time, never took the time to see it documented like this. What I really discovered is that the 45 ACP doesnt in most instances "headspace" on the case mouth.

[slamfire1]

This is a 48 round group at 25 yards, offhand, on my Gong target. This was fired in a M1911. I pick up range brass, bought buckets of "once fired" military brass, have reloaded the brass an un known number of times, and never segregated the stuff by any classification, never trimmed it, and it shoots just fine.

A bullseye shooter might think different.

As for high primers, on another forum a gentleman stated he had a high primer go off in a revolver. Seems the cylinder recoil had enough force to push the primer against the recoil shield and ignite it.

This must be very, very rare. I have been able to find lots of slamfires in Garands, due to that free floating firing pin, but only one account of a slamfire in a handgun.

Though, I recall reading accounts of rounds going off in a M1911 if the pistol was dropped with a round in the chamber. Hard to believe, especially as the firing pin has a rebound spring, but enough people were hurt that now M1911's have firing pin blocks.

[Allen]

Anyone know how much the 40 cal and others are affected by case stretch? How many times they can be fired before case length is a concern?