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-   -   40 S&W XD cartridge headspace (http://www.firearmstalk.com/forums/f59/40-s-w-xd-cartridge-headspace-72796/)

hdog 09-19-2012 09:34 PM

40 S&W XD cartridge headspace
 
I have a question about headspace. SAMMI specs limit lengths to 0.850" -0.010". I have some cases for reloading that have been fired one or more times that measure between 0.8365" and 0.8459" (they were given to me). My question is, what dangers are there in reloading those that are up to 0.0035" under limits? Do cases expand in length as in bottleneck rifles.

Coyotenator 09-19-2012 11:35 PM

My books say MAX case length is .850" and trim to length is .840". The one number you posted is between those two.
Are you using a 1/10,000" caliper or mic , because if not, you got one to many decimal places there.

genesis 09-20-2012 12:09 AM

Quote:

Originally Posted by hdog (Post 947297)
I have a question about headspace. SAMMI specs limit lengths to 0.850" -0.010". I have some cases for reloading that have been fired one or more times that measure between 0.8365" and 0.8459" (they were given to me). My question is, what dangers are there in reloading those that are up to 0.0035" under limits? Do cases expand in length as in bottleneck rifles.

I reload for the 40 S&W, which is a high pressure round (relatively speaking). I haven't had any length issues yet, but I've only reloaded my cases 4 or 5 times. Take the barrel out of your gun and use it as a go/no-go gauge. Drop in a factory round and note how far the round seats in the chamber. Now drop in a re-sized case and see where it seats. With a light beginning charge, you shouldn't have a problem.

Just as a side not, I use a Lee tumble lube 175 grain SWC ahead of 3.6 grain of Winchester 231 powder for around 750 FPS. This functions my Ruger SR40C just fine and the recoil is nill. Makes an excellent plinking/range/practice load. And while I load up with Hornady Critical Defense ammo in my Ruger GP100 at night, my "pet load" in my SR40C would do some damage if need be. It's my "New York reload".

Semper Fi

Don <><

hdog 09-21-2012 12:57 PM

Coyotenator,
I am using a Starret 0-1" mic (old style, not digital) which will read to 0.0001, if read carefully. I also check a digital caliper against it. The caliper is not as accurate as the mic in my opinion. I listed the mid range case dimensions only to indicate they are all over the place in length and that some are good to go. My concern is damage to the gun due to a small gap due to the short case. Please note that I am an amatuer at this and only know what I read. I do not want to damage my XD by doing something foolish like using out of tolerance cases.

Thanks for the replys.

Coyotenator 09-22-2012 12:59 AM

I use a Lee case trimmer for my XDSC.40 practice ammo.If I don't feel contact or see chips coming off I will mic it, and if it is more than .005" too short I toss it.I haven't had a single FTF and certainly no damage with this policy and truthfully I have only had to toss a dozen or so cases out of thousands because of this.

hdog 09-30-2012 11:55 PM

Coyotenator,
Does your statement "more than .005" too short" mean shorter than .835"? Or do you mean shorter than .845" (.005" less than SAMMI nominal length)? Sorry for my confusion.

Coyotenator 10-01-2012 12:27 AM

Quote:

Originally Posted by hdog (Post 959748)
Coyotenator,
Does your statement "more than .005" too short" mean shorter than .835"? Or do you mean shorter than .845" (.005" less than SAMMI nominal length)? Sorry for my confusion.

Sorry, that wasn't clear the way I put it.


What I meant was that if the case was more than .005 shorter than my trim length of .840".

I felt that a max .005" difference would still function dependably and safely for practice ammo.I have fired several thousands of these rounds thru my XDSC and haven't had any FTFs or any sign of other problems with ammo or pistol.

hdog 10-01-2012 11:24 PM

Thanks coyo,
That's what I thought, but wanted to be clear. I plan on jumping in tonight to cull my cases.


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