Large pistol primer instead of large rifle?

[Kawfeegod]

Well, considering that the primer market is pretty much dried up in my neck of the woods, large rifle primers are non-existant. I am sitting on quite a few LP primers and was wondering if you could sub a LP primer for a LR primer? Anyone have any ideas?

[Down South]

From what I understand, the cup on a LP primer is shorter than a LR primer. I’ve heard of it being done but I’ve never tried to use LP primers in rifle cartridges. If what I’ve heard about the LP primer cup being shorter is true then the primers will be more recessed than normal. This possibly could cause a FTF. Another thing and again from what I’ve been told is, LP primers are not as hot as LR primers. Some folks with more knowledge than me will chine in on this one I’m sure

[jsizemore]

And the primer cup is thinner on a pistol primier. It's not meant to operate at rifle pressures.

[archmaker]

Digging deep into my past I vaguely remember that the thickness of the cup material varied between LP and LR. LR has slightly thicker material to help with the pressure, where LP had a thinner material so that the weaker "blow" would fire.

That may not help.

[curator]

I use large pistol primers all the time on my cast boolit rifle loads. I do keep pressures below 40,000psi for many reasons. I get good ignition and accuracy. They do sit a bit lower than LRPs but I have never had a failure to fire in any rifle using them. Occasionally the pistol primers give better accuracy. My best .308 load with Lyman #311291 and 16 grains of Alliant 2400 shoots 3/4 inch 5-shot groups at 100 yards with LPP and 1 1/2" with LRPs--who would guess?

[cuzinbruce]

A large rifle primer pocket is deeper than a large pistol primer pocket. If the primer is seated to the bottom of the pocket, it will be unsupported at the bolt face. By the difference in depth. If it is seated flush, it may move when struck by the firing pin, causing unreliable ignition. Unsupported, it might leak or worse. Also made softer as pistol firing pins typically don't strike with as much force as a rifles. Designed for a lower pressure environment, from 16,000 to 35,000 psi for pistol cartridges, normal to magnum. Rifle pressures would probably be expected to range from 40,000 to high 50,000's. I don't think it would be a good substitution.

[jcwit]

Not recommended, thats why they make Lg. Pistol & Lg Rifle.

No further comment!!!

[JohnH]

From my own experience I have fired quite a few thousand rounds of cast boolits in rifle cases lit with with large pistol primers with no problems. We must however disucss the loads to get good working parameters. 10-12 grains of Unique in a rifle case will make anything go bang and does not need a rifle primer. I have found that 12 grains of Unique under a 120 grain boolits in a 25-06 case does give better accuracy when lit by a rifle primer, but in a tight, pistol primers work just fine. I've never been able do discern any difference between large pistol, large pistol magnum and large rifle primers when using 19 grains of 2400 with the same 120 grainer in my 25-06. Nor can I say with absolute certainty that large rifle primers perform any better than large pistol primers in the 30-30 with similar powder charges under boolits as heavy as 180 grains.

Now would I use a large pistol primer as a substitute in a standard pressure loading in a rifle case? No. Nothing catastrophic will happen. You will get pierced primers, and depending on the gas control of your rifle, you may or may not get an eyefull of gas and tiny debris. Over time, the gas will erode your firing pin and firing pin hole/bushing which will end in primers prematurely showing cratering.

Be wise. If the load you are considering is operating at pressures greater than 35,000 psi or so don't use a pistol primer. If you are using a load that is comparable in powder charge weight and bullet weight to a known good pistol load using a pistol primer, then by all means use a pistol primer.

[trickyasafox]

I never thought to use LP instead of LR with reduced unique loads, but that will certainly save me some money! LP I have a fair supply of- LR, that was getting dicey!

[JIMinPHX]

I've been told for years that rifle primers were thicker than pistol primers so that they would be able to handle the higher pressures that rifles generate. I was also told that pistol primers needed to have softer cups so that the dainty little firing pins in them could work reliably. I always just assummed that to be true. I always thought that the dimensions were exactly the same.

I just went out into the shop & measured unfired WLP & WLR primers. The rifle primer was about .004" taller. That difference is the same as the thickness of a sheet of standard 20# copy paper. The cup materials were the same thickness. The anvils looked to be a slightly different shape, but were pretty close. The pellets were different colors & the rifle primer pellet looked to be a bit bigger. I did not test cup hardness.

I've used pistol primers before with lite loads in small rifle calibers with good luck. I'm sure that there is a point where this becomes inadvisable, but I don't know where that line needs to be drawn. As always, I recommend that you err on the side of caution.

[WARD O]

Substituting LP for LR in black powder shooting is not an uncommon practice. Many seem to think the milder LP is an aid in accuracy with black powder. Black powder pressures are mild and there seems to be very little if any down side. Some say that after many thousands of round there might be minor bolt face damage due to primers setting back during firing.

It sounds like this is to be a short time substitution for you until primers become more readily available so that should not be an issue for you.

So, if you keep pressures to the levels these LP's were designed to handle they should pose no problem for you.

Ward

[Kawfeegod]

So I am getting yeahs and nays, which is what I expected. It looks as though it might be worth a shot in a pinch. I'll load a few and see what happens in my mosin.

[BerdanIII]

Add another yea; I just burned up over 1000 Magtech 2 1/2's in an M39 (7.62x54mmR) and Ishapore .308 with gallery loads with no problems whatsoever. I have also used them in commercial rifles with no trouble. The Cast Bullet Association handbook recommends large pistol primers in cast boolit loads for ex-military rifles. The only caveat I would place on this is to make sure your firing pin(s) have rounded, not sharp points.

[wildwes]

I've never tried them with cast loads, but I tried 20 rds of them in 8MM Mauser in my 1903 Turkish mauser once, and they wouldn't ignite the powder. The load was 42 grns of BL-C(2) I think, with a sierra 150 grn prohunter PSP. The primers detonated just fine, and generated enough force to push the bullet into the barrel, but not detonate the powder. I think they lodged about 4 inches from the front of the chamber. I hate to think of what would have happened if I had fired a round behind them without removing the bullet every time. And boy did the BL-C(2) make a heckuva mess in the action. Maybe they would work fine with another powder, idk

[drinks]

Before everyone gets their panties in a bunch over LR and LP primers and the supposedly .010 difference in height, try measuring the depth of the primer pocket in several different cases and several different manufacturers.
I tried about 15 and found a depth of .123 to .136 in just rifle cases.

[jdgabbard]

Ok, so we know that LP primers run the risk of not handling the pressure very well above 30,000. But what if we were to use magnum pistol primers? Since the magnum loadings are designed to operate at higher pressures it would seem these primers would be able to handle a little more...

What do you think?

[wildwes]

I don't know enough about it for my thoughts to count for much jdgabbard, but it would look to me like the magnum primers would be able to handle the pressure ok if it wasn't extremely high. Wouldn't they do a little better at igniting the powder too?

[Screwbolts]

I have a wonderful old Stevens 322C in 30/30 that likes to shoot Ohaus 180gr RNGC. this particular rifle will misfire on the first strike if I load w/ LR primers. some time ago I tried LP primers with it and have never had a miss fire with LP primers. I load a Book load of AA 2520 28 gr I believe and it has never been shot with anything but cast and LP primers for the last 5 yrs.

Ken
CNY

[GrizzLeeBear]

I've never tried them with cast loads, but I tried 20 rds of them in 8MM Mauser in my 1903 Turkish mauser once, and they wouldn't ignite the powder. The load was 42 grns of BL-C(2) I think, with a sierra 150 grn prohunter PSP. The primers detonated just fine, and generated enough force to push the bullet into the barrel, but not detonate the powder. I think they lodged about 4 inches from the front of the chamber. I hate to think of what would have happened if I had fired a round behind them without removing the bullet every time. And boy did the BL-C(2) make a heckuva mess in the action. Maybe they would work fine with another powder, idk

Correct, wrong primer for the powder. Thats why its recommended to use a magnum primer with ball powders. The deterant on ball powder responds to a hotter, more powerful primer much better. You basically went to a weaker primer instead of a more powerful one. If you did get any to fire, did you get cratered or pierced primers?

I've only tried LP primers in a rifle load once so far. Shot some 100 gr. plated pistol bullets in a Rossi 7.62x39 single shot loaded with 5 gr. of 231. I was also worried about the primer sitting a little deeper because this rifle doesn't have a lot of firing pin protrusion, but all 10 that I loaded fired just fine and were very accurate. Would have worked with this load more, but the rifle is at the smiths getting rechambered to .303 British right now. I'm going to continue this experiment in the .303 when I get it back.

For low pressure gallery/small game type cast boolit loads I don't see any problem using pistol primers. The primer seating deeper may or may not cause problems in a particular rifle, but it seems that most of the time its not a problem.

[wildwes]

Correct, wrong primer for the powder. Thats why its recommended to use a magnum primer with ball powders. The deterant on ball powder responds to a hotter, more powerful primer much better. You basically went to a weaker primer instead of a more powerful one. If you did get any to fire, did you get cratered or pierced primers?

I figured it might have had a little something to do with the powder being a ball powder, I know they tend to be a little harder to ignite. I only tried three, because they made such a mess, if I remember right, one fired, but I may be wrong. It's been a little while, so I don't remember for sure. But as far as I remember there weren't any problems like cratered or pierced primers, just a little "clunk" sound as the primer detonated and pushed the bullet into the bore. I took the other 17 rounds, pulled the bullets, replaced the primers, and reassembled them. Problem solved. lol.