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Oops! Used LR primers when I should have used LP

hill billy

Sergeant
Full Member
Minuteman
Mar 7, 2009
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Los Angeles, CA
Made up 200 rounds of medium pressure .45 ACP tonight and didn't notice until I was done that I had some large rifle primers slipped into my stack of large pistol and I had used them. Looking back they seemed to seat a with a little more difficulty. It's plinking stuff, should I run it? They are only about 750 fps loads. I'm dreading 2+ hours of pulling them apart if not. Ah, shouldn't reload when I am tired.
 
Re: Oops! Used LR primers when I should have used LP

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Re: Oops! Used LR primers when I should have used LP

It depends on the powder you used. Also, I doubt they are sitting flush with the casehead and will cause feeding issues.
 
Re: Oops! Used LR primers when I should have used LP

I've done the same thing with 9mm and used small rifle primers, they shot just fine in my pistols.
 
Re: Oops! Used LR primers when I should have used LP

Small Rifle and Small Pistol primers are dimensionally the same. Large Pistol primers are shorter than Large Rifle. LR primers stick out when sitting in a LP primer pocket.
 
Re: Oops! Used LR primers when I should have used LP

The primers do stick out a bit. I am running 4.2 gr of Tite Group so by no means a max load. Oh well, I'll shoot some today and see what happens.
 
Re: Oops! Used LR primers when I should have used LP

As 918v stated the large rifle primers are taller. They will slam fire in a semi auto, ask me how I know, be carefull.
Woody
 
Re: Oops! Used LR primers when I should have used LP

I had two of fifty that failed to fire on repeated attempts cause the primers were high. Even repeated cycling wouldn't do it. They had what looked like light primer strikes. Other than that the others fired fine in the Glock I was shooting them out of.
 
Re: Oops! Used LR primers when I should have used LP

Per the SAAMI specs on primer, pockets, chambers, and cases:

Depth min max diameter min max
small rifle primer pocket .117 .123 .1730 .1745
small pistol primer pocket .117 .123 .1730 .1745
Large rifle primer pocket .125 .132 .2085 .2100
Large pistol primer pocket .117 .123 .2085 .2100


Height min max Diameter min max
Small rifle primers .115 .125 .1745 .1765
small pistol primers .115 .125 .1745 .1765
large rifle primers .123 .133 .2105 .2130
large pistol primers .115 .125 .2100 .2120"

The LRP could stick out .0045" of the large pistol pocket, or they could stick out .0005", but probably somewhere in between.



The range of brass is from .888" to .898"
The range of chambers is from .898" to .920"

That means the headspace could be from .000" to .032"

If you are following the arithmatic, you would need a long case, short chamber, shallow pocket, and long primer to get .0045" of interference, which would not set off the primer anyway.

How do I know that?
I shoot large rifle primer in 45acp rifle chambers that very very tightly chambered, and I do not have problems.

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Re: Oops! Used LR primers when I should have used LP

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hill billy</div><div class="ubbcode-body">I had two of fifty that failed to fire on repeated attempts cause the primers were high. Even repeated cycling wouldn't do it. They had what looked like light primer strikes.</div></div>
Betcha those were keeping the slide from closing that last little bit. Does the barrel come all the way up in the ejection port/locking recess with those rounds?

I had one [nameless] pistol that had the sear and firing pin block a bit uncoordinated, so the FP would clip the block--not quite clearing each other. Damaged both metal faces. The same thing *could* happen with a Glock trying to fire if the slide is more than 1mm back from fully in battery. It's how the trigger bar interfaces with the FP block.
 
Re: Oops! Used LR primers when I should have used LP

Not only that, it's a KB just waiting to happen as the gun will fire out of battery and unlock prematurely.