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7.65/.32 headspacing, redux

711 Views 5 Replies 4 Participants Last post by  Kar98
I'll post this here, since it applies to .32 Walthers; mods, move it if necessary.
A '35 Beretta followed me home today; the '35 is the 7.65 version of the '34, which is a .380.
'Plonked' both some of my own (taper crimped) reloads, and some factory Fiocchi. The reloads seated solidly against the chamber step, with just a smidge of space between the cartridge rim and the breech. The (somewhat more of a roll crimp) Fiocchis plonked in easily enough, but were less willing to come back out. In the Fiocchi case, the rim also remained a tiny bit above the breech opening.
So the jury still appears to be out; it's less than clear if the .32 is to headspace on the chamber step or on its own rim. In this case, it was certainly the former.
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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.

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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.

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Thanks, Mike. All that makes sense; over time, it's apparent that dimensions which mfgs accept tend to, shall we say, drift a little. Not factored in is the likelyhood that a too short case (not the semi-rimmed .32) will headspace on the extractor.

BTW, the '34-'35 is a wonder of sturdiness and simplicity (the disconnector is amazing), tho' not so refined as our Walthers. Our late range officer was a huge fan of these Berettas, which was a motive in buying this one.

Anyone know anything about a walther ppk .32 eagle n with k suffix
OMG you HAVE a thread, keep your questions about your pistol to THAT thread instead of tacking onto all kinds of random threads. Please.
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