Pic of large rifle primer vs. large pistol magnum primer

[ophidia]

Due to the primer shortage, I've considered using large rifle primers instead of large magnum pistol primers for .44 magnum H110 loads, mostly due to the following facts:

1. I can't find large pistol magnum primers
2. Win WLP primers don't seem to give a complete burn with H110 in my Desert Eagle
3. I am curious as to how they'll work.

As a beginning to this idea, I primed a case with a Remington large rifle primer and a case with a CCI large pistol magnum primer. I then popped each one off in my Desert Eagle.

Here are the results:



As you can see, the firing pin indent is much lighter on the rifle primer (left hand case), upholding the "rifle primers are thicker/harder than pistol primers" fact. They both went BANG! with no problems. The CCI primer was much louder, though (not that this definitely means anything). The rifle primer was also flush to slightly raised, while the pistol primer was slightly below the case head.

I plan on loading up a clip full of each with middle of the road loads of H110 and testing this out to see how it performs with the large rifle primers. As shallow as the indent is on the rifle primer, I'm not convinced that they will reliably ignite.

Comments welcome.

[Magnum Wheel Man]

you could possibly relpace the firing pin spring with a heavier spring if you intended to use rifle primers regularly... are you sure the rifle primers will regularly seat deep enough to prevent slam fires from the slide ???

[ophidia]

The rifle primers aren't flush, so slamfires are a concern... I'll know within the next few days. I wonder if anyone makes a heavier spring for it-- I'll have to check into that if this works out. Of course, magnum pistol primers would be preferable, but one has to work with what one can find, I guess.

I'll have some results w/in the next few days.

[dwwhite]

I don't think I would try it...

#1
A large rifle primer is slightly taller than a large pistol primer, as you have noted, it will not seat flush, or below flush, as is required for safe loads. Will this result in a slam fire? I don't know, however, I wouldn't want to find out, especially in a cartridge as enthusiastic as a .44 mag with a case full of H110. While this may not happen when manually cycling the slide, it very well could under recoil.

#2
If I am not mistaken, a large rifle primer ignites much more energetically than a large pistol primer. This can result in pressure spikes, especially given the relatively small case capacity of a pistol cartridge. I have done some experimentation with small rifle primers (which are dimensionally identical to small pistol primers) in 9x23 cases, and found that a safe charge over a pistol primer is WAY over pressure with the rifle primer.

#3
This is the most minor issue, but as you have noticed, I think you'll experience light primer strikes and misfires.

This advice is worth what you paid for it, but as I stated before, I think I'd put the project on the shelf untill you can find the proper primers. The supply chain is starting to open back up and if you keep your eyes open, you should be able to find some in the not too distant future.

[GeauxTide]

In rifle tests, the manufacturers showed that LRMag primers can increase pressure from 8-10k over LR. Just kiss your hand and your pistol before each session.

[Unclenick]

Dw is correct. These are not compatible. Only the very few high pressure (50-60 kpsi) pistol rounds that are designed to use rifle primers should use them, and their primer pocket depth is formed accordingly.

The danger is the high primer allowing ignition that precedes the cartridge and bolt getting fully into battery. Out-of-battery ignition is dangerous for the same reason playing with dynamite caps is dangerous. Metal fragments fly out and can seriously injure whoever is in their path, so the shooter to the right of your ejection port is at risk. On another forum we have a member who was a gun tester and firearm failure investigator at Aberdeen Proving Grounds who described investigating an out-of-battery cartridge burst in a machine gun that killed the soldier exposed to the ejection port blast. It's nothing to fool around with.