9mm Luger Headspace


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dlsjm
January 17, 2008, 07:34 PM
I bought a 9mm Stoeger Cougar. My first auto handgun. I have been doing some reading on how to put some loads together for this thing. I'm concerned about headspace and pressure problems. I have measured a bunch of my cases and have found some as short as .746 some around .750 and some .754.

What is excessive headspace in inches?
How short can a 9mm case safely be?

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Jim Watson
January 17, 2008, 07:50 PM
Variable case length of autopistol brass is very common and it will not have any noticeable effect on standard loads in a service pistol.

I kept getting a few Boxer primed 9.2x18 Makarov cases in with mailorder "once fired" 9mm P. They went through the Dillon with no difference in feel on the handle, unlike .380. I caught them on gauge inspection and pulled the bullets for salvage. Until I asked myself, what if I let one slip by? So I left a couple loaded and shot them. They fed, fired, and functioned normally, in spite of another .039" excess headspace.

Maybe if you were shooting PPC or Service Pistol with a 9mm target pistol it would pay you to use brass of the same lot number as long as you could find. But not for routine use.

CZ57
January 17, 2008, 07:55 PM
dlsjm, you don't have to worry about the .746" case length. While trim length recommendations will vary, .744" is very common and .010" shorter than max case length of .754". Lyman recommends .751", but in most cases you're not likely to get there. Most brass that I run across once fired from factory loads hovers right around the .744" trim length with some of it even shorter than that. As far as buying virgin brass, I've had the best luck with Starline that will run around .750".;)

FieroCDSP
January 17, 2008, 10:09 PM
Jim Watson, if you collect or still have some of those 9x18's I'll buy them off you. I have a PA63 I load for .

OP, while the mouth of the case usually headspaces the case, the extractor usually does a fair job of keeping the case within range of the firing pin. I also have a Stoeger Cougar 9mm and I love the thing. I use almost exclusively reloads in it, and I've never had a problem with feeds or short cases.

caz223
January 17, 2008, 10:17 PM
I stick with WIN headstamps, as they are free, plentiful, and tend to be very consistant in case length at about .748, most of the range pickup brands are all over the map.

Jim Watson
January 17, 2008, 11:16 PM
Fiero,
Sorry, when I said a few, I meant a FEW. Perhaps half a dozen (that I caught) in 3500 mixed brass from Brassman.

BigG
January 18, 2008, 08:31 AM
The Luger cartridge is also a taper fit in the chamber. Although it is said to headspace on the mouth (like 45 ACP) it really slides in until it wedges in against the taper.

The Bushmaster
January 18, 2008, 10:26 AM
BigG...You'll need to explain why my 9mm X 19 loaded rounds enter the chamber of my 92F and my M43 with a clunk as the case mouth strikes the chamber end. I believe that the taper is for better feeding then as a form of head spacing. Also after the cartridge has been fired the taper is gone...

asknight
January 18, 2008, 07:16 PM
Bushmaster, I don't think you're hearing the brass mouth crash into the chamber leade over the volume of the noise of the breechface slamming the rear of the chamber. In fact, I'm willing to wager on the fact that the sound will be nearly identical if you didn't have a loaded magazine in at all (aside from the sound of the round being stripped from the magazine).

The Bushmaster
January 18, 2008, 09:30 PM
I'm talking about dropping the cartridge into the chamber with the barrel out of the frame. There is only one sound and that is the case mouth striking the chamber lead...

rcmodel
January 19, 2008, 11:17 AM
+1
9mm case taper has nothing at all to do with headspace, or anything else.
The case head-spaces on the case mouth, just like all other straight-wall pistol cases.

If you don't believe it, drop a 9mm round in a Glock barrel sometime.
There is still enough room left inside the chamber that it will rattle if you shake it!

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

CZ57
January 19, 2008, 01:56 PM
+2, and if you measure up from the case rim by .2" you'll have the correct location for measuring casehead expansion. You can compare fired cases to unfired rounds from the same control group. Chamber dimensions will fluctuate among brands, but I try to keep casehead expansion from exceeding .001" when working up warm or +P 9 X 19mm loads.;)

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