7.65/.32 headspacing, redux

In a blowback it may not matter that much. If the cartridge headspace is insufficient to fully seat the cartridge, the forward momentum of the slide will probably squash it into zero headspace and all will be bright and beautiful in the world. Or, the insufficient headspace will be less than the tolerance of the disconnector --in which case the slide will be closed enough to allow the sear to release the hammer to fire the cartridge. So if it's not grossly deficient AND if you're not a handloader trying to eke out the last reload from a weakened and worn-out cartridge case, you'll still be fine because the stronger web of the case wall will be the only part not fully supported by the chamber when it fires.

Same thing if the cartridge headspace is excessive. The cartridge case acts like a piston and shifts rearward to bear against the breech face to push the slide open. Again, so long as it's not 'way out excessive or involves a flawed case, it's not likely to rupture.

Locked breech pistols generally involve double the chamber pressures, and are much less forgiving.

M

Moon, if you want to know (for purely academic satisfaction) how the .32 ACP is SUPPOSED to headspace (at least in American practice), the quick way is to refer to SAAMI maximum cartridge & minimum chamber drawings. A quick glance shows that .32 ACP headspaces, theoretically at least, on its semi-rim. There is a .010" tolerance on chamber headspace, from .045" to .055", while the maximum cartridge rim is .045".

Correspondingly the case OAL is .680" -.020", while the straight length of the chamber is deeper, .693" + .015" before reaching a 15-degree bevel. So unless the cartridge case is overlong, it will not seat against the front chamber step. Any resistance or sticking felt is probably from excessive case OD at the crimp.

Of course this has nothing to do with a Beretta M35, which was not made to SAAMI specs (or for that matter, probably not to CIP specs either.

M