Large pistol primers in 'low pressure' rifle loads?

[Kraschenbirn]

Anybody tried this? Right now, I've got a lot more LP primers on hand than LR and, over the weekend, got to thinking (yeah, I'm aware that can be hazardous at the reloading bench) while I was prepping brass for a couple of my old milsurps. As I was cleaning the primer pockets, it came to me that my CB loads in those, for the most part, use pistol/shotgun powders and are shot at 'reactive' targets (like plastic pop bottles) on the 100-yd line. Now, I knew that LP primers are slightly shorter than LRs (.118 vs. .128, respectively) but went ahead and tried a few LPs in empty 8x57 and 7.62 Russian brass and they fired just fine. Next step on the ladder will be, of course, to load up some of my regular 'plinker' rounds using LPs to see how their accuracy compares with the same powder/boolit combination using LR primers. But, the idea seems so darn simple that someone else must have already tried it so, before I press on, can anyone suggest why it's not gonna work or why it's such a bad idea?

Bill

[zarrinvz24]

It’s been done before. Some cartridges, like 22 Hornet, specify pistol cartridges. Just start at starting loads and work up cautiously.

[Calamity Jake]

With cast boolit loads, all I use is LP primers, I've also shot J words reduced and LP primers

[Loudenboomer]

Yes. I have done it with light loads in the 45-70. It's not the best idea. As you know they are shorter so proper seating will mean the primer sits deeper than flush. This can give the primer an opportunity to move around. It will also make your firing pin have to reach the extra 10 thousandths. In times of shortages we improvise where we have to. With 10 to 12,000 psi loads I never gave it a second thought. I'd never do it with high pressure loads. Be safe my friend.

[MUSTANG]

Keep in Mind that a Large Rifle Primer is "Taller" than a Large Pistol Primer is; and the Rifle primer pocket is "Deeper" than a Large Pistol Primer pocket.

Attachment 291768

[JohnH]

I used to shoot a lot of 30-30 from a Marlin 336 and a Savage 340 using large pistol primers and Green Dot under the RCBS 30-150-CM. Load made ~1300 fps. I also used large pistol primers in 30 Herrett cases when shooting the Lyman 3118, and the same charge of Green Dot in my Contender

[Texas by God]

I've used large pistol primers (for cast bullet loads only) in the 22-250, 25-06, 30-30, 30-40, 38-55, and 8x57 successfully. No pierced primers and no failure to fire. I made a note about it on my bench and returned to using large rifle primers.
After reading about it here; I also gutted some dead large pistol primers and seated live small pistol primers inside and seated them in 30-30 brass. They worked too.
Knowledge is handy.

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[sigep1764]

Echoing above, no worries for me in Red Dot loads for 30-30 and 270. SPP in 223 with W748 and cast at 2000fps is my go to. As long as they are "cast boolit pressures", I have not seen an issue.

[cwtebay]

I will echo the above offered advice about using the LPP.
I would like to ask those that offered this - why with cast bullets only?
Perhaps I am playing a little bit of Devil's Advocate here - but could you please explain how cast with LPP would be safer than jacketed with LPP?

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[mehavey]

Cast bullet pressures -- not just cast bullets only
FWIW, I'll use pistol primers when loads are 30,000 psi or less, or BP
-- usually cast alloy country,* fast[er] powders, easier ignition.


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[MUSTANG]

The thickness of Pistol Primers tends toward a thinner metal in the cup than compared to Rifle Primers which tend toward a thicker metal. I have used small pistol primers in .223 Bolt and Ar platform rifles; one does what they have to when getting primers is difficult.

[Rainier]

I loaded the 35 Whelen successfully with pistol primers, Bullseye or W231 powder using 168gr SWC’s. Accuracy wasn’t great with either powder combo but the SWC’s came out the end of the barrel and hit the target. The rifle is a Model 70 and the firing pin reaches the primer.

[Nobade]

This is pretty common in the black powder cartridge world. The milder pistol primers often give better accuracy than rifle primers. You can punch the primer through a sheet of paper so a little disc is between it and the case to partially take up the difference in height as well as blunt the explosion a bit to further reduce the power. Keep in mind that continued use of pistol primers can and will eventually peen the breech face if it is not hardened as the primer gets a running start before it hits the face since it has more room to move.

[Baltimoreed]

I would also add that the op doesn’t mention primer brand. CCI primers [dark blue boxes, don’t know if the new CCI box is cosmetic or the primers have been changed] are supposed to be harder than other brands, federal primers are the softest. Rifle fp springs are a lot stronger than handgun fp springs so there is a real potential for a pierced primer. Be careful.

[bigboredad]

I've done it in a 45-70 using Winchester for both rifle and pistol on average I'd get 5fps difference. I quit buying rifle primers after that

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[15meter]

Only problem I've had was on one single rifle with one batch of PPU brass, an English double in 8x50R. It was in 8x56R brass that was cut down and necked down to the 8x50R. Issue was primer pockets that were too deep. Standard rifle primers, no problems.

loaded them in at least a dozen different milsurp/english vintage calibers with light cast loads. 16 grains of 2400 or a reasonable equivalent with no other issues.

[414gates]

Depends on powder quantity in the case.

A primer has to provide the heat to ignite the powder column.

When you're in the region of handgun grains of ball powder, the heat of a LP primer is enough.

When you go into rifle quantities of extruded powder, you need more heat.

A LP primer can ignite a rifle cartridge, it may not do so reliably in all cases, or in all weather conditions.

The proper fitting of a LP primer in a LR pocket is a separate issue.

[Sig556r]

458 SoCom uses LPP since parent case is 50AE, max pressure in the books at 35ksi.

[Old Caster]

Kraschenbirn I just sent you a message about primers.

[MostlyLeverGuns]

Some feel large pistol gives better accuracy in the smaller rifle cases (30-30, 32-40, 38-55, 32 Spcl). Pressure not usually a problem with NORMAL cast bullet loading. I use them in some 30-30 and 32 Special loads. One Theory is a milder primer gets the powder burning befor the bullet starts moving for a more uniform powder burn - like small primers in the 6.5 Creedmoor and .308.