Home Forums Reloading Handgun Reloading Magnum Primers

I'm nearly out of regular primers for my .357, but I still have a number of magnum small pistol primers.

Would it be safe to substitute magnum primers for standard primers if I start with the lowest listed load of 2400? I usually shoot 14.2 - 14.4 grains of 2400 with absolutely no issues. I'd like to drop back to the manual's starting load of 13.8 grains of 2400 and use magnum primers in place of standard ones, and watch for pressure signs. Thoughts?

I have found no detectable difference in velocity or apparent pressure between standard and magnum primers in the .357, .41 and .44 magnum cartridges.

Thoughts ..you say for .357 that should use a magnum primer to start with. Depends on your load and how much pressure you got using a standard primer you run the risk of piercing which runs into other problems

It has always been said to use standard primers with 2400 powder. I have never used magnum primers with 2400 in my 44 magnums. Never used it in 357, so I can’t answer your question.

I almost always use WLPs in my .44 magnums and .480Rugers with 2400.

Works for me.

I have heard the same regarding magnum primers with 2400 and also Accurate #9. I believe it was due to erratic pressures as these powders are easy to ignite. I don't recall where I read this but I suspect it was from Handloader magazine in either a Pet Loads article or the one one heavy weight bullets in the 357 mag as those are what I have read most recently.

Seems like I remember the old Speer manual used magnum primers with ball powders. Caliber didn’t matter. Hasbeen

Earlier Speer manuals used magnum primers with 2400 in the 357 magnum. Then several years ago, they reshot their data and they found standard primers worked better than magnum primers. They put a note to that effect in their write up on the cartridge.

For older guns where I worked up 2400 loads using magnum primers , I still use them. For more recently purchased guns, if I’m going to use 2400 I take Speer for their word and start with standard primers

I don’t have all my manuals in front of me but the Speer #13 manual has that note in the cartridge profile

That sounds to me like the reasonable way to go about it. I don't think you'll have a problem doing it that way.

I'd be tempted to use a chronograph though, especially if you want to ease back up in charge weight.

No problem. 2400 lights easily and isn't affected noticeably by magnum primers. At least that is my experience in 44mag. I don't see the need to reduce charges - 2400 is a very well understood powder.

It's probably fine with light or medium loads but you should be very careful of max loads in the .357 with 2400 and magnum primers. There can be upwards of 5K PSI greater pressure with magnum over standard pistol primers in that situation. Back in the '80s I was pushing the throttle hard on some Sierra 110s over 2400 trying to get past expansion into fragmentation for varmint shooting. The light and middle loads were ok-ish. The near max and max loads, according to book data, was giving me a very strange sensation of detonation and being slapped around the pants cuffs when the shot would go off. Lookin' back that gives me the "someone stepped on your grave" chills. It's a damned good thing the GP-100 is a stout gun.

Tom

Pretty sure Pearce suggested standard primers with AA9 but I could be wrong. I’ve used standard primers with both .357 and .44 Mag loads with AA9 with no problem. Last time I loaded.357 it was a hat full for future use and I went max book load from Western Powder. Their data used WSPM so I went that route. Too, I had a carton of WSPM with nothing to use them in but .357 so saved my standard small pistol for other uses, times being what they are.

I have a bunch of Oregon Trail 158gr lswc bullets loaded with 14.5grs of 2400 and magnum primers for my GP100. O/T data called for mag caps. I only shoot them in the Ruger, and they more than not get carried in cold temps.

I've read that 2400 gives more consistent pressure variation with standard primers. But like the OP I had more of the mags on hand.

No complaints, no signs of over pressure. Shoots to the sights, and knocks through 5+ inches of phone book with enough confetti for a parade.

That’s my load also, magnum primers have worked for years with no indications of too much pressure and very good accuracy.

Magnum primer cups are a little thicker than standard primer cups.
I have seen standard primer cups get pierced due to excessive pressures when used in Magnum max loads. This can lead to firing pin erosion if done consistently over time.
If the pressures are moderate in a load, standard primers should be fine.

To me 14+ gr of 2400 is pretty stout load in a .357 with 2400.

My .357 load is 13 gr of 2400 Winchester primer which is snappy in my 4" Ruger Security Six, but it is the most accurate in that and my Rossi Model 92, .357. I would not hesitate too switch to mag primers with that load. 13.8 is probably OK, but it was not as accurate for me.

Different use, but I load up a lot of .357 with 38 sp loads. With Universal Powder, a 158 gr PC bullets and CCI magnum small primers is more accurate than W231. However, W231 with a std small pistol primer is more more accurate, both using 4.6 gr

Posted this video in previous thread

I run Rem SR 7.5's in my 9mm....40.....& 45 ACP striker fired SA's

No issues......

SP primers have gone extinct.....

Plenty of 9mm factory ammo out there though

I used to use CCI 550's in .357 with 2400 but, mostly use standard now. Never noticed an accuracy difference. I have chronoed some loads with 2400 though and get more consistent velocities when I use Magnum.

I actually found Fiocchi small pistol primers yesterday. Regular, not magnum. Box of 1200 was going to run over $180 though, so I demurred.

https://lohmanarms.com/product/ginex-small-pistol-primers/

$84.99 for 1K or $424.95 for 5K + shipping + haz-mat + state sales tax. I ordered 3K of them and the shipping was prompt. With what I have on hand, I'm probably set for life, considering my age and consumption rate. Some say they have a tendency to be a bit tight. I primed 100 used .38 SPL brass with them with no problems. A few were a little tight, but nothing at all that was anything that I would say as being any kind of an issue. All seated well. All were primed using a hand held Lee priming tool. I have not fired any of them, but all reports I have seen say they work just fine. They all look good - no apparent visual defects seen.

those Ginex are good primers. I recently got some large rifle by them