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Discussion Starter · #1 ·
I have some cases that are .726 inches and am concerned about the firing pin not being able to set off the primer and have a misfire. How short can I go to be safe. I am loading for a Glock 34 and a CZ p10c.
 

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^ THIS

It is a rare 9mm semi-auto which headspaces by the case mouth physically contacting the front of the chamber.

The next cartridge usually is tilting and rising and then it slides up under the extractor hook during the feed cycle, and as WeeWilly says the cartridge is then held sufficiently snug to let the firing pin do its job.

I have never, ever measured the case length of 9mm Luger brass before loading it when I make general purpose ammo.
 

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Discussion Starter · #6 ·
Sounds great! I thought it headspaces on the case mouth. Didn't know the extractor hook holds the case. That's why I turn to the you guys (The Experts)! Learn something new everyday, keeps me on my toes.
 

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Sounds great! I thought it headspaces on the case mouth. Didn't know the extractor hook holds the case. That's why I turn to the you guys (The Experts)! Learn something new everyday, keeps me on my toes.
You are correct,it is supposed to head space on the case mouth however the extractor in reality does more to affect actual head space. SJ 40
 

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The minimum case length, by the book, is .744. Max is .754.

The issue I see is whether you are getting a decent taper crimp since your cases are so short. If these are mixed with normal cases that could be a problem since your dies will be set up to correctly crimp one length and not the other.
 

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Discussion Starter · #10 ·
The minimum case length, by the book, is .744. Max is .754.

The issue I see is whether you are getting a decent taper crimp since your cases are so short. If these are mixed with normal cases that could be a problem since your dies will be set up to correctly crimp one length and not the other.
Believe it or not, I measure each case and seperate them in 3 piles, less than .742, greater than .748 and the sweet spot between the two. I do it for that reason, to make sure my crimp is enough to remove the slight bell and straiten the case mouth as y'all have talked about so much. So, I also case gauge each one especially when I am starting to make sure the crimp is just right, very slight indent on the precision delta 147gr bullet if any indent at all. When I get enough long cases I load those then switch to the short ones then back to the .745 (lots of those)
 

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Believe it or not, I measure each case and seperate them in 3 piles, less than .742, greater than .748 and the sweet spot between the two. I do it for that reason, to make sure my crimp is enough to remove the slight bell and straiten the case mouth as y'all have talked about so much. So, I also case gauge each one especially when I am starting to make sure the crimp is just right, very slight indent on the precision delta 147gr bullet if any indent at all. When I get enough long cases I load those then switch to the short ones then back to the .745 (lots of those)
That sounds like a lot of work to keep loading out of spec cases. Within spec, I don't see the need to change the crimp settings on your dies. But .726 is well out of the ballpark, being .02 away from a .01 acceptable range.

This is one of those things that the nature of pistol construction and the relatively low pressure of 9mm lets you get away with, but you can get away with firing .380 in a 9mm. Some guns will even cycle. So it is up to you how much effort you want to pump into doing the wrong thing right. I would just be inclined to chuck the short stuff and stop thinking about it afterwards.
 

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You are correct,it is supposed to head space on the case mouth however the extractor in reality does more to affect actual head space. SJ 40
Actually for all service rounds, regardless of caliber.
 

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Sounds great! I thought it headspaces on the case mouth. Didn't know the extractor hook holds the case. That's why I turn to the you guys (The Experts)! Learn something new everyday, keeps me on my toes.
It does headspace on the case mouth. The extractor may or may not hold the round in place depending on the condition of the extractor. Even with a strong extractor, the case is being held in place a small corner brass. Plus, if the extractor is loose, the case slams back against the breech face. Not good long term.
 

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Actually for all service rounds, regardless of caliber.
This isn't true. Any handgun or rifle that uses a pop-over extractor won't function correctly if the headspace is too far off. Being controlled by the extractor is only true of controlled round feed systems.

AR15, Makarov, P7, G3 are all examples of pop-over extractors and non-controlled round feed.
 

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I too have never measured a 9mm case.

I load them from 5 gal buckets, haven't touched my die settings in years. The taper crimp and belling work kind of in unison, the shorter cases get less bell the longer a little bit more and vice versa on the crimp die which is only there to straighten the case enough for smooth chambering. I suppose if I was loading lead, I would be a little more precise, like in my 45 Auto loads. Since I load jacketed almost exclusively in 9's, the belling is a little less critical, the crimp is just taking it back to a known dimension.

Since I do chamber checks on all my ammo, I can't remember the last time I had a feed failure in one of my Glock 9's.
 

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This isn't true. Any handgun or rifle that uses a pop-over extractor won't function correctly if the headspace is too far off. Being controlled by the extractor is only true of controlled round feed systems.

AR15, Makarov, P7, G3 are all examples of pop-over extractors and non-controlled round feed.
Reality, it is unlikely to get perfect headspace of ANY pistol round unless the chambers & brass match. So the extractor will in effect hold the case in place for headspace. Controlled round feeding or not. Why you can fire a 380 in most 9mm & it will go bang.
 

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Cases get longer with use, not shorter. The only way to end up with short 9mm cases is because someone cut them too short. If I found that, I'd recycle them.
Again, not always true. Fire a service round case that is perfectly in spec 10X, measure that, get back to us. They do NOT appreciably grow, some will even shrink a tiny bit.
Case lengths are all over the place, depending on who manuf them, not because of trimming. In 40yrs of reloading I have never trimmed any service pistol case & some have been loaded 15-20x. They vary little in length, even with mixed head stamps.
 
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