Military primer pockets - 9mm

[RainDodger]

Hey, everyone -

I've run into an issue I've not seen before. I've loaded thousands upon thousands of 9mm rounds over the last 4 decades and never had a problem.

I happened to acquire roughly 15,000 once-fired military cases. I started sizing and priming them. I've primed with CCI, Winchester and Remington primers, and I've seated them with either a bench-mounted priming tool, or a heavy single stage press. The primers are all well-seated in the bottom of the pockets.... and it appears to me that the pockets are deeper than I've seen before. The primer is certainly not flush with the case head - it's sitting depressed a couple of thousandths probably.

Out of 100 rounds loaded, I might see 7 or 8 failure-to-fire cartridges, and I think it's the primer depth that's causing it. They're simply too deep. (Obviously, you can't purposely NOT seat the primer deep enough so it remains flush with the case head, or it won't detonate that way either.)

My question is - you guys that load military brass... have you seen primer pockets that are deeper than commercial brass?

I REALLY, REALLY, REALLY don't want to send 15,000 once-fired 9mm cases to the recycler....

 

[moxie]

What's the headstamp(s)?

Typically, primers that are seated correctly all the way to the bottom of the pocket are slightly BELOW flush, enough so that you can feel the difference with your finger. So from what you've said I don't see a problem at all.

You note that, "Out of 100 rounds loaded, I might see 7 or 8 failure-to-fire cartridges". Does this mean you think they will fail or you've actually had failures?

 

[LiveLife]

Depending on the primer pocket depth, .002" below flush may not be enough to set the anvil tip against the priming compound (pre-compression

With some cases, primer pocket depth will vary and seating primers flush or slightly flush will only bottom out the anvil feet against the primer pocket but the anvil tip won't be in contact with the priming compound. If these loads don't fire, additional primer seating depth may be required to push the anvil tip against the priming compound (pre-compression) so the initial firing/striker pin hit will ignite the priming compound.

As many suggest, seat primers FIRMLY until you feel the initial pressure (anvil feet contacting bottom of primer pocket) AND secondary pressure (anvil tip setting againt the priming compound/top of primer cup flattening).

With most primers, I aim for .004" below flush but have tested them to .008" below flush and they have all gone bang (see comparison picture below) - http://www.thehighroad.org/showthread.php?p=9911556#post9911556

If they have crimped primer pockets, be sure to remove the crimp or the primer cup will hang and only flatten so the anvil feet never touches the bottom of the primer pocket.

.004" below flush on the left vs .008" on the right (notice flattening of primer cup with .008" below flush)

 

[ReloaderFred]

I seat my primers -.004"/-.005" below flush. The anvil has to be seated into the primer pellet or it won't fire. Anything less is marginal.

I've loaded many thousands of 9x19 U.S. military cases, and prefer it for the heavier case walls. The crimp must be removed prior to repriming or you'll have problems seating primers.

Hope this helps.

Fred

 

[RainDodger]

Yes I do know how to seat primers and what they require to detonate.

I just measured their depth compared to some loaded commercial and military rounds.

The commercial/military rounds run from flush, to about .002" below flush.

My failures-to-fire were about .009" below flush. That indicates to me that the pockets are really deep - likely at the extreme range of most firing pins. I guess I'll compare actual pocket depth to commercial brass.

Oh, it's also not the gun - it's happening in multiple H&Ks and CZs.

In answer to one of the questions above - all kinds of NATO-marked brass, and yes, I have removed the military crimps and no, I haven't deepened the pockets when removing the crimp. I know someone will ask that. I've also primed some without removing the crimp and run into the same depth issue. It's sort of interesting in a sucky way... sucky in that I might not be able to use any of this brass.

 

[LiveLife]

.009"? That's really deep.

At some point, primer cup will be too deep for the firing/striker pin to indent the cup/priming compound against the anvil tip.

I would deprime a random sample of cases and if primer pockets are too deep for reliable primer ignition, measure all the primer pockets and cull/scrap deep primer pocket cases for bulk brass.

 

[moxie]

Really strange.

Fact is, the primers in the cases you got functioned as designed, so it's hard to figure what is wrong now.

Is there any correlation between any specific headstamps and the cases that had primer failures?

Finally, I know you had the same depth issue with cases you've primed without removing the crimp, but have you had any failures among this group?

 

[RainDodger]

I agree, moxie. It's weird. Later this weekend I'll sort through and see if I can make any sense of whether there's a headstamp correlation.

I was talking to my gunsmith buddy and he figured maybe they're using some different primer now - maybe slightly taller or something like that. Who knows. If they do that, it will certainly make our handloading lives more complicated.

What I do want to do is, de-prime some and compare the pocket depth to commercial cases. That will clarify things.

bds - yeah, I had failures in both groups. The reamed ones and the ones that still have the crimp in place.

When/if I figure this out, I'll post what I find.

 

[LiveLife]

I was talking to my gunsmith buddy and he figured maybe they're using some different primer now - maybe slightly taller or something like that.

Not likely as taller primer cups would be above flush in "standard" cases.

Are you sure the primer pockets have not been modified?

If they are once-fired military cases, they should still have primer pocket crimps.

If they don't the primer pockets could have been swaged/modified.

So you are having deep primer pocket issues with cases with crimps?

 

[RainDodger]

I just did a bit of investigating:

I grabbed a handful of military cases and punched the primers out.

I grabbed a couple of factory commercial rounds, removed the projectile, then punched the primers out.

I measured the depth of the primer pockets.

They’re all close, and ALL within SAAMI specs: .117" - .123" for small pistol pockets.

My newest hypothesis: in my eagerness to fully seat primers, maybe I over-seated them. Maybe I actually crunched them too much. I took those military cases, reamed out the crimp and “lightly” seated the primers fully, but with no substantial crush. They’re damn near flush, or maybe .001”-.002” recessed. <sigh>

I may have been too heavy-handed… to the tune of a few thousand.

This is weird, but perhaps true. Now I’m going to go sit on my deck and contemplate life with a cold glass of ice tea.

 

[cheygriz]

I've used American MilSurp 9MM brass forever and never had a problem. I swage the pockets, and seat them by feel to the bottom of the pocket. They are all below flush, and never misfire.

I've never seen any reason to measure seating depth because they're supposed to be seated to the bottom regardless.

 

[Rule3]

I have removed the military crimps and no, I haven't deepened the pockets when removing the crimp. I know someone will ask that. [/B]I've also primed some without removing the crimp and run into the same depth issue. It's sort of interesting in a sucky way... sucky in that I might not be able to use any of this brass.

Well as you brought it up

How did you remove the crimps? I was going to ask if the brass had been "processed" were they did the primer removal and primer pocket ream.

The brass originally had been primed, and as far as I know, there is not "special" military primer for the 9mm. SPP are standardized.

 

[RainDodger]

Although I own a swager, I never use it. I ream all my cases on a Hornady case prep machine. A reaming bit cannot deepen the pocket though, if that's what you're thinking.

I think I know my problem... I really am thinking that I just used a little too much poundage when seating these primers. I've used a bench mounted priming machine since the 1970s, and I've only recently used the priming function of a Redding Ultra-mag press... and the leverage is considerable. I'll do some further experimenting.

 

[Rule3]

Yes you may be really mashing (technical term) the primers. Only thing i can think of without actually seeing them.