Small pistol versus small rifle primers in .357 Mag/.38 Special

[beagle]

Once upon a time, the loading manuals recommended small rifle primers for the .357 Magnum cartridge. This practice has fallen by the wayside over the years. I've always used small pistol primers in the .357 Mag and .38 Special with good results and no ignition problems except with some of the slow burn ball powders (WC820, AA9 and H110) in the .357.

I suddenly find myself blessed with an abundance of WSR primers.

What does the brotherhood say to using them in the .357/.38 Special? Any experiences good or bad. Any pressure signs observed. Any body tested them one against one with the same load of regular powders (Bullseye, Unique, Herco)./beagle

[M-Tecs]

This is from another site:

I contacted CCI back a couple years ago and asked to speak to their primer tech. I was connected with a wonderful woman who had worked there for 37 years. I asked her the following, "What is the difference between your SPM primers (550) and your SR primers (400). Specifically, what's the difference between their size, their cup thickness, the primer compound, and amount?"

She pulled out the data sheets on both and compared them. As she was reviewing them she casually mentioned that, "You know small pistol and small rifle primers are the same size. It's the large pistol vs large rifle where the rifle primers are slightly taller." After her review of the sheets (I could hear them rustling), she replied that their specs showed that they were the same size, the same cup material and thickness, the same primer compound, and the same amount.

I asked her if that meant that they were the same item boxed in different packaging. She replied, "I've been reloading myself for over 20 years and I only buy SR primers (400)." We chuckled and I thanked her and said good bye. I use Wolf SR primers in all my 38spl and 357mag loads and have had no issues in slightly over 4,300rds so far.

[Rcmaveric]

I use small riffle primers as magnum small pistol primers in .357 Mag. It was tried with safety amd caution in mind and worked up to safe and acceptable load.

[rancher1913]

always heard that sr would work fine in a pistol but you sometimes had problems using sp in a rifle.

[Lloyd Smale]

yup at least for cci small rifle and small pistol mags are the same primer. Id have to guess for the other brands theres not enough difference between them to worry about it.

[dragon813gt]

I use CCI and have always used SR primers. All of my loads are worked up w/ them. I didn’t want to keep SPM for a single revolver at the time. Having to stock less items means more of the ones you need.

[quack1]

I was gifted several thousand CCI 400 a few years ago, so did a comparison of WSP, my usual pistol primer, and them, with mild 357 loads Bullet was 358495, powders were 3gr/bullseye and 3.4/red dot. Gun was S&W 19 6" barrel. Accuracy was best with the WSP primers, but not by much. Velocities were about 50fps higher with the CCI 400 with both powders. Points of impact with the CCI 400 were lower than with WSP and required a small sight adjustment with both powders. I shot up all of the CCI primers without any problems.

[sutherpride59]

This is a great thread, I’ve been trying to find magnum primer for my 357 for the last weeek and never even thought about using small rifle primers.

[Reddirt62]

During the great Obama drought I reloaded thousands of 9mm with SR with no issues. FWIW.

Sent from my SM-N950U using Tapatalk

[Forrest r]

I use these primers for:
357's
9mm's
223's
https://i.imgur.com/psC0I4B.jpg

Did some testing with a short bbl'd 357, H110 & those primers pictured above last week. Low sd/es with the 158gr/357/H110/primers pictured above.

[Ed_Shot]

I jump on SR primers when I see them on sale... all I use for 357 any more. Agree with Reddirt62, when large pistol primers were hard to come buy I found that SPM and SR primers worked just fine in 45 ACP small primer brass.

[beagle]

Kind of what I was figuring. I knew there was a metal thickness difference but I expected the priming compound to be about the same. Since I am not a hot rodder with my loads, I should get by fine.
Thanks for the responses guys./beagle

[Dragonheart]

Small pistol & small rifle are basically the same primer the difference is the hardness/thickness of the metal. If your firing pin hits hard enough then it doesn't make any difference other than a hard hit can punch a hole in a soft primer. A light hit may not fire a hard primer. CCI primers are harder primers and Federal are the softest. Winchester and the others fall somewhere in between. If you have a tuned handgun, which usually will have a lighter strike, I would choose Federal Primers. I use Winchester for everything else.

[Hick]

I got a little distracted one day when priming cases for my 38 Special and my 223 Remington-- put the wsp primers in the 223 cases and the wsr primers in the 38 cases. Neither load caused any problem, and they shot to the same POI as with the proper primers. While I would not ordinarily do this, I'm convinced my firearms don't care which they get.

[trapper9260]

I have read this post to the end and learn something. I have read different things also and this breaks it all down to understand better.Thank you

[Harry O]

Back during the Obama shortages, I ran short of small pistol magnum primers for the .357 Magnum. I did have small rifle primers. I used them. No problems with ignition in several revolvers and no excess pressure signs. Used them for 3 or 4 years.

[mvozz]

Interesting thread! All over the internet I have been told to use sp primers for my 22 Hornet. I have used CCI small rifle for 30 years but wanting to experiment I decided to give it a try. My standard load is 10grs of H110 and a 40gr projectile. Different primers - same results. I saw no increase in accuracy that everyone said I would see. Just maybe this thread explains that.:grin:

[marek313]

As many others already answered the only difference between (at least CCI) SPM and SR is the thickness of the cup. Since I couldnt find SPM around me I started using SR as replacement for 357 Magnum and I never looked back. My Ruger GP100 MC has no problems with SR primers and you probably wont neither unless you installed some super light hammer springs.

[WRideout]

This is from another site:

I contacted CCI back a couple years ago and asked to speak to their primer tech. I was connected with a wonderful woman who had worked there for 37 years. I asked her the following, "What is the difference between your SPM primers (550) and your SR primers (400). Specifically, what's the difference between their size, their cup thickness, the primer compound, and amount?"

She pulled out the data sheets on both and compared them. As she was reviewing them she casually mentioned that, "You know small pistol and small rifle primers are the same size. It's the large pistol vs large rifle where the rifle primers are slightly taller." After her review of the sheets (I could hear them rustling), she replied that their specs showed that they were the same size, the same cup material and thickness, the same primer compound, and the same amount.

I asked her if that meant that they were the same item boxed in different packaging. She replied, "I've been reloading myself for over 20 years and I only buy SR primers (400)." We chuckled and I thanked her and said good bye. I use Wolf SR primers in all my 38spl and 357mag loads and have had no issues in slightly over 4,300rds so far.

I once had an abundance of CCI SR primers, and a dearth of SP primers of any description. I used the SR primers in my 38 spl with no noticeable problems.

Wayne

[Tom W.]

Well well, I have a few boxes from when I was loading for a .454.

Now I know what to do with them......

[megasupermagnum]

I received an email from CCI with the same info. I never got a clear answer on any other brand, but I swap CCI SPM and SR without worry. I usually find the SPM cheaper, and more available so I use those.

I heard the same thing with 327 federal about using small rifle primers, and that can run up to 45k psi. I've used all primers successfully, and choose the one that is most accurate or consistent with that particular load. Another note about CCI primers, the small pistol cup thickness is EXACTLY THE SAME is the small pistol magnum. The only powders I've found so far that work better with the magnums in 327 federal is AA #9 and H110. Every other powder I have much better results with standard primers. The Federal small pistol primers are very thin, and do get nice and flat with max loads, but I've never had one pierce or leak.

[porthos]

ok: how about using large rifle primers in large pistol cases or the other way around??

[Dave W.]

ok: how about using large rifle primers in large pistol cases or the other way around??

Large rife primers are longer than large pistol primers, so they will not seat properly in pistol cases. Do not substitute one for the other.

[BNE]

Great read, you all taught me something today! Thanks!

[Dragonheart]

Large rife primers are longer than large pistol primers, so they will not seat properly in pistol cases. Do not substitute one for the other.

Dave is right, you could probably get away with it in a pinch with a revolver, but I would be afraid of a slam fire in a pistol. I have interchanged the small primers a lot, but never tried the large.

[Landshark9025]

I received an email from CCI with the same info. I never got a clear answer on any other brand, but I swap CCI SPM and SR without worry. I usually find the SPM cheaper, and more available so I use those.

I heard the same thing with 327 federal about using small rifle primers, and that can run up to 45k psi. I've used all primers successfully, and choose the one that is most accurate or consistent with that particular load. Another note about CCI primers, the small pistol cup thickness is EXACTLY THE SAME is the small pistol magnum. The only powders I've found so far that work better with the magnums in 327 federal is AA #9 and H110. Every other powder I have much better results with standard primers. The Federal small pistol primers are very thin, and do get nice and flat with max loads, but I've never had one pierce or leak.

emphasis mine

I would question this. You may be right and it would be worth checking, only because my experience has been different. I have a S&W Mod. 66 that I shoot mostly 38 SPL loads out of. I use CCI-500 religiously. At one point during "The Drought" (I think it was 2015) I tried some CCI-550 and got a lot of light primer strikes. This was the only time I experienced that. I was trying to do some load workups to see if there would be a difference and it happened often enough to make it not worth it. I'd say at least one every 10 rounds.

This particular revolver is old, I acquired it second hand and it had been shot a lot. So it's possible it has a light spring or a worn firing pin. All I know is that with this particular firearm, in the several thousand rounds before and after, using CCI-500 I never had a failure, but with the few I tried with CCI-550- it was pervasive.

Naturally, this was all using the same cases, same press, same everything else.

[Rcmaveric]

My understanding is the that the difference between SPM is SR primers is the hardness of the primers. The SR are harder to resist the higher pressures of riffles. While the SPM is softer for use in lower pressure rounds IE 38 spl.

[Lloyd Smale]

there is more variation between the cup hardness of different brands then between different primers of the same brand. A cci small or large standard pistol primer is harder then a fed mag small or large rifle primer.
My understanding is the that the difference between SPM is SR primers is the hardness of the primers. The SR are harder to resist the higher pressures of riffles. While the SPM is softer for use in lower pressure rounds IE 38 spl.

[Thundarstick]

My experience with the 327 FM is that almost everyone gripes about the double action revolvers having a hard trigger pull. I started replacing springs in one of mine and polishing a little. It would shoot 32HR mags with SP primers 100% but with factory Federal rounds would give FTF about 25% of the time. This before I was aware the factory loads do use SR primers. I've found through experience that SPM primers and SR primers do seem to take more or less of a bit to set them off. My advice would be to test the SR primers in your gun for sure!

[MT Gianni]

My understanding is the that the difference between SPM is SR primers is the hardness of the primers. The SR are harder to resist the higher pressures of riffles. While the SPM is softer for use in lower pressure rounds IE 38 spl.

That is what we have been told since the 50's in gun magazines. It currently appears that bean counters may have decided it was easier to stock one materiel. Eash manufacturer is different though I can see this happening. I know my 1955 I frame 32 long will go bang on recent SR primers.

[megasupermagnum]

emphasis mine

I would question this. You may be right and it would be worth checking, only because my experience has been different. I have a S&W Mod. 66 that I shoot mostly 38 SPL loads out of. I use CCI-500 religiously. At one point during "The Drought" (I think it was 2015) I tried some CCI-550 and got a lot of light primer strikes. This was the only time I experienced that. I was trying to do some load workups to see if there would be a difference and it happened often enough to make it not worth it. I'd say at least one every 10 rounds.

This particular revolver is old, I acquired it second hand and it had been shot a lot. So it's possible it has a light spring or a worn firing pin. All I know is that with this particular firearm, in the several thousand rounds before and after, using CCI-500 I never had a failure, but with the few I tried with CCI-550- it was pervasive.

Naturally, this was all using the same cases, same press, same everything else.

I can't speak of hardness, but the thickness of CCI 500, 550, and 400 are all .020" thick cups the best i can measure. Federal 100's are only a little thinner at either .016" or .017", but a lot softer. If you're not careful, you can pre-flatten Federal primers when seating them. I would think hardness would effect strength, but my point was that every regular small pistol primer I've tried has held up to 45k psi loads no problems. I have not noticed any gas leaking or pierced primers. Certainly you wouldn't run into problems with the slightly lower pressure 357 mag.

In response to both Landshark9025 and Thundarstick, I tried a 9# hammer spring in my 327 federal GP100, which most people will tell you it didn't work for them. I had a light hammer strike about 1 in 20-50 shots, and both CCI 500 and CCI 550 primers performed identically poor. I never tried Federals with that combo, as I did not want a gun that could only use one primer. I tried a 10# hammer spring, and did not have a misfire in 100 shots, but it just seemed like the hammer was too slow to me, and I did not trust it. I now have the Wolff 12# in the gun, with zero misfires and hundreds of rounds downrange, including factory ammo. I do not have a trigger pull gauge, but double action is not bad at all, I would bet around 9#.

Realize this is just my experiences, so take it with a grain of salt. I did just shoot a bunch of ammo primed with brand new CCI 500's. I can measure them tomorrow to see if the thickness has changed from the last batch I had bought maybe 5 years ago.

[nicholst55]

Some action pistol shooters use nothing but small rifle primers. As long as your gun(s) will ignite them reliably and you work up to your load with them, I personally see no issues. I have loaded a small amount of .40 S&W with SRPs, and experienced no problems.

[sutherpride59]

Has anybody tried the opposite and used small pistol magnum primers in smal rifle loads? Seems like small pistol magnum primers tend to be cheaper.

[megasupermagnum]

Has anybody tried the opposite and used small pistol magnum primers in smal rifle loads? Seems like small pistol magnum primers tend to be cheaper.

Yes, I have used CCI 550 in 223 remington. No difference from the 400.

[dale2242]

I have used small rifle magnum primers in my GP100 357 with heavy loads of slow powder with no issues.
I have never had a FTF with them....dale

[ioon44]

Has anybody tried the opposite and used small pistol magnum primers in smal rifle loads? Seems like small pistol magnum primers tend to be cheaper.

I loaded F-100 small pistol primers in .223 by mistake and the primers ruptured so soft pistol primers won't work for small rifle.

[dwtim]

At least with CCI SP primers, I just confirmed that the dimensions are the same with my mic.