Originally Posted by
RC20
While shooting a gun has far more to do with other aspects than head space, I will say its up to the owner to satisfy themselves.
What I can say is that all the 1917s I have tested have had a generous head space to the point it would almost close on field reject.
As these are military guns, they did not meet SAMMI (do not, SAMMI did not exist when these were made).
You don't need to neck size (and if you do you have to full size 4 or 6 cycles)
I do minimum shoulder bump back and have no issues. That being you adjust your FL die to move the shoulder back a couple of thousandths (.002)
The first firing (assuming the head space is not too long) the brass fire forms to THAT chamber. After than it won't grow and you should be good for normally amount of reloads (more if you minimum bump back and or anneal)
A great deal has been made about head space. There are really two things to it.
1. If its too long the round won't fire because the case moves forward as the firing pin hit the primer and there is no smack to the anvil, no boom.
2. If its too short you can't close the bolt.