Large vs Small Primers

Like most of us here I have to buy what's on the shelf, if somethings on the shelf. Magnum pistol primers are the most common around here, with magnum small rifle making a showing too.
In my Ruger bolt gun chambered for the 7.62x39 I need to use something besides standard Large Rifle primers just to conserve primers for my .270 Winchester. So I loaded and shot a few 10 shot groups using Federal Large Pistol Magnum and Winchester Large Rifle primers. I also loaded CCI Small Rifle primers against Federal Small Pistol Magnum. With a charge of 20gr's of IMR 4198 and using Arsenals' 312-155gr boolit I ended up with these groups for velocity. W-W brass for the Large and Hornady brass for the Small.
Large Rifle- 1761 fps
Large Pistol Magnum- 1693 fps
Small Rifle- 1693 fps
Small Pistol Magnum- 1692 fps
The small primers gave the most concentric groups so I'll work more with them.

I loaded a bunch of tokarev 7.62x25 the other day w a bunch of primers I just punched out of range brass from finding it and bad reloads I was given. Small rifle and small pistol alike. Accuracy didn’t change much from pistol range aspect but was always curious how the reverse would look. Considering large pistol primers should handle 35k pressure from a Beowulf, does it handle the 762x39 well enough to feel safe?

It does in my opinion. Accuracy at the 100 yard line was more concentric with the pistol primers in this instance. I've since used RL-7 and H322 with loads producing 1800-1900 fps and things appeared fine. Some of the load information has pressure ratings and some didn't.

While it’s apples and oranges I’ve been using small primer 45acp brass and small primer .455 brass to conserve my stash of lpp to use in my cas rifles [45colt, 44-40 and 38-40]. I traded off all my spp for lpp and am using srp in my 38, 45acp and 455 as I have plenty srp. Can’t really tell a dif. Everything is cci. Hard times with no end in sight.

small primers can usually be interchanged among rifle and pistol.. just watch for pierced [primers when youing a pistol primer in a rifle. On the other hand.. lr and lp do not interchange well... one may not seat fully.. the other can be over seated.

On the stand point of subbing large rifle magnum for large rifle.
Not going full pressure loads, just cast data. Where does that fall? Will the mag primer push the boolit out before a good powder ignition? Bad anything? Lower powder charge?
I have a lot of mag rifle primers from some years ago when I goofed around with the magnum craze, don't see that coming back to my bench for awhile.

To further your experiment, try SP or SR INSIDE of a LP or LR gutted and reflattened outer case.
I tried it once and it worked (after reading about it here).

Ajohns- I've been using LRM primers for cast loads for some time to conserve my supply of LR standard primers. No drama whatsoever.
Sent from my SM-A716U using Tapatalk

Thanks, I'll have to try it out and see:smile:

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Originally Posted by Ajohns

On the stand point of subbing large rifle magnum for large rifle.
Not going full pressure loads, just cast data. Where does that fall? Will the mag primer push the boolit out before a good powder ignition? Bad anything? Lower powder charge?
I have a lot of mag rifle primers from some years ago when I goofed around with the magnum craze, don't see that coming back to my bench for awhile.

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I frequently will sub magnum for regular primers when loading ammo for cold weather use.

Also..when loading 357 mag plinking rounds..i use standard primers...etc

Nice too hear some others experience, paying close attention to seating depth is a must.

I have AND AM USING LARGE PISTOL PRIMERS IN 7-10 WATERS ANd PAY CLOSE ATTENTION TO THE SEATING DEPT. sO FAR NO PROBLEM. uSING tight Group powder. Like to hear from others who have used similar loads.

I recently got my hands on some CCI #34 "For 7.62mm Ammunition Large Rifle Military Primers" (plain white box) and tested them also with cast loads in 30-30, 32 WS, M1 Garand, 7.65 Mauser and 303 British. They worked well in all the rifles and performed similar to a LR Magnum primer.

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