Small Rifle Primers for 357 Magnum?

[RoyceP]

I recently got a box of 1960's Winchester small rifle primers from an antique store. There were 81 primers in the box, but the price was so insignificant I didn't care.

I don't load any rifle calibers but several of my loading manuals say that a small rifle primer can be used in several different 357 magnum loads, particularly some with WW 296 and Hercules 2400 powders.

Anyone tried this? Comments?

 

[Unclenick]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

Small rifle primers are the same physical size as small pistol primers, and you will find a number of folks on YouTube who have substituted them for small pistol magnum primers without a problem. However, you occasionally hear of revolvers, especially the tuned ones with trimmed springs, having trouble with the thicker cups some makers use in rifle primers. Also, given their age, the primers you have may be different enough in their formulation that I would probably want my starting load to be with a powder that you can load down, like 2400, and not with one you can't, like 296. I would start with it at a starting load and see how your velocity compares to what magnum pistol primers give you, first, assuming you still have some.

This is an abundance of caution on my part. They will probably work fine, but with handloading, erring on the side of caution is a good policy.

 

[RoyceP]

I just googled the topic and came up with a lot of folks using nothing but small rifle primers in 357 magnum. Lots of stuff on the Cast Boolit forum. I don't have any 296 so it's just as well. I tend to use lighter loads as my shooting is more for accuracy than to make big fire clouds. I stocked up in the late 1980's with a lot of Hercules products and likely have a lifetime supply of powder.

I will try it with my sub 25,000 CUP Hercules 2400 load and see how it performs.

 

[Shadow9mm]

I have used both winchester and CCI small rifle primes with H110/W231 and Power Pistol with no issues in 357 mag.

 

[RoyceP]

Winchester 231 (1980's version) is another powder that I have on hand so I will try that too. Thanks!!!

 

[44 AMP]

231 is a "fast" powder, easily ignited with standard primers. Unless magnum primers are all you have, using one to light off 231 is a waste of a magnum primer.

If possible, save the magnums for where they are needed. Same applies to small rifle primers being used in place of magnum pistol primers.

 

[Shadow9mm]

231 is a "fast" powder, easily ignited with standard primers. Unless magnum primers are all you have, using one to light off 231 is a waste of a magnum primer.

If possible, save the magnums for where they are needed. Same applies to small rifle primers being used in place of magnum pistol primers.

Oh I agree, I would never waste a small pistol magnum unless that is all you had. But we are talking small rifle. In my experience 231 does not need it, but is not hurt by it either.

 

[Jim Watson]

Trivia: Before Federal offered magnum primers, they recommended their small rifle primer for .357 Magnum.

 

[RoyceP]

I've been reading online that power levels are nearly if not actually identical regarding most manufacturer's small rifle / magnum small pistol primers. The difference is the cup the primer is made of - the small rifle primer is designed to withstand much higher pressures.

The consensus I am seeing is that they work fine for most people in 357 Magnum, the only ones that seem to have trouble have lightened (aftermarket) springs in their revolvers.

 

[jetinteriorguy]

It’s not only an issue with lighter trigger/hammer springs for good ignition, but also the difference between shooting SA and DA. With revolvers the DA is usually lighter than the SA pull and primer ignition isn’t as dependable. I’m loading some up with SRP’s today and have several revolvers to test with. I’ve been testing in my 9mm’s and so far the only one that’s been about 99% reliable is my CZ75SA, so for range fodder that’s acceptable. All my striker fired pistols were about 75% or less for reliable ignition. This is with S&B SRP’s.

 

[Shadow9mm]

It’s not only an issue with lighter trigger/hammer springs for good ignition, but also the difference between shooting SA and DA. With revolvers the DA is usually lighter than the SA pull and primer ignition isn’t as dependable. I’m loading some up with SRP’s today and have several revolvers to test with. I’ve been testing in my 9mm’s and so far the only one that’s been about 99% reliable is my CZ75SA, so for range fodder that’s acceptable. All my striker fired pistols were about 75% or less for reliable ignition. This is with S&B SRP’s.

Tried winchestee and cci small rifle in a p365, lc9s, g19, gp100, and lcr 38spl. No ignition problems.

 

[jetinteriorguy]

Tried winchestee and cci small rifle in a p365, lc9s, g19, gp100, and lcr 38spl. No ignition problems.

I’ll have to give this a try. I have a fair amount of CCI SRP’s on hand and can always use the S&B’s in my rifles. Thanks for this info.

 

[Shadow9mm]

I’ll have to give this a try. I have a fair amount of CCI SRP’s on hand and can always use the S&B’s in my rifles. Thanks for this info.

I have been using the win and cci in 9mm, 38spl, and 357 mag. I have tested them against standard small pistol and small pistol mag in all 3. Velocities were within about 10-15 fps higher with the SRP. Just like when changing primer brands, it's recommended to work up from start. But I have switched all my primers over to small rifle to make stocking easier.

 

[jetinteriorguy]

So far I’ve at least established the S&B SRP’s work about 98% in two of my pistols. At least they are my two favorites, myCZ75SA and my slicked up GP100. The occasional misfires have all fired on a restrike, even though I’m cramming them in and seating them pretty firmly. One last test platform is my Henry BBS .357mag, which I’m assuming they should pretty much be a 100% in, I’ll either test this today or Monday. So for range use I’m good enough with the S&B primers.

 

[Shadow9mm]

Glad it's working well for you. I must be lucky, I'm still at 100% with cci/win. Trying federal here soon, but I expected no problems, always heard they were more sensitive.

 

[rodfac]

...also the difference between shooting SA and DA. With revolvers the DA is usually lighter than the SA pull and primer ignition isn’t as dependable.

Yep and by a surprising amount in some guns.

If you have ignition troubles, I'd suggest re-checking the strain screw for the mainspring. I had a problem just yesterday with a M-66 Smith that burped on several CCI 500 primers...the screw had backed out 1 full turn. A first for me in 60 years of shooting S&W DA revolvers. Rod

 

[jetinteriorguy]

I’ve loaded up a box of .357 and a box of 9mm using some CCI SRP’s to see how they work. I don’t have any Smith’s in .357, just my GP100 and my Security Six so no strain screws. I am running lighter springs for the hammer springs, but I’d just as soon not go heavier since I do have a ton of ammo loaded with SPP’s and a little over 4000 left on the shelf. Funny thing is the GP100 main spring is lighter than the one in the Security Six, but has been the most reliable by far. I’ll be testing these on Wednesday morning after a doctors appointment.

 

[jetinteriorguy]

So my final testing was pretty successful, in a limited fashion. I put 50 rounds through my two most finicky 9mm’s using CCI SRP’s with 100% success, where before using the S&B’s barely 25% success. I also put 50 rounds through my most finicky.357 with the same before and after results. As one last test of the S&B’s I put 50 rounds through my Henry BBS .357 with one misfire that fired on the second try, so for range use I’d say a successful outing all in all.

 

[Shadow9mm]

So my final testing was pretty successful, in a limited fashion. I put 50 rounds through my two most finicky 9mm’s using CCI SRP’s with 100% success, where before using the S&B’s barely 25% success. I also put 50 rounds through my most finicky.357 with the same before and after results. As one last test of the S&B’s I put 50 rounds through my Henry BBS .357 with one misfire that fired on the second try, so for range use I’d say a successful outing all in all.

Sounds like a win! It's been working well for me.

 

[jetinteriorguy]

Sounds like a win! It's been working well for me.

I’m glad you suggested it. Ya learn something new every day, if you’re paying attention.