Small Pistol Primers for .357 mag?

The standard SPP is perfect.

With 700x you will not need magnum primers. If you are concerned, get some Winchester primers as they work for both standard and magnum apps.

There's just a handful of powders that require magnum pistol primers in .357 Magnum loads. It's the powder make that determines it, not the cartridge designation.

Don

If I'm not mistaken, I believe Win Small Pistol primers come in both Standard and Magnum. Their Large Pistol Primers are Standard/Mag combined into one.

MtnCreek is correct. Winchester has WSP & WSPM. Their WLP they say are good for both regular and magnum loads.

Never have used any 700x yet, but I have used non magnum primers in 357 with Titegroup and W231. The powders both did well.

I believed you would want magnum primers if you were to use slower powders as AA #9 or 2400.

As said above, SPP are just fine because your powder doesn't require a magnum primer. Hard to ignite ball powders like H110 / W296, HS-6 and HS-7 should be set off by a magnum primer.

Load them up without worries...

kcofohio said:

I believed you would want magnum primers if you were to use slower powders as AA #9 or 2400.

Click to expand...

Alliant, manufacturer of 2400 recommends against the use of magnum primers with 2400 and claims that standard primers give more consistent ignition.
HS-6, HS-7, H110/W296 do require Magnum primers for .357 mag.

There's just a handful of powders that require magnum pistol primers in .357 Magnum loads. It's the powder make that determines it, not the cartridge designation.

Click to expand...

Exactly!

Far as I know, the WSP and WSPM are the same primer in different packaging.

kcofohio said:

MtnCreek is correct. Winchester has WSP & WSPM. Their WLP they say are good for both regular and magnum loads.

Never have used any 700x yet, but I have used non magnum primers in 357 with Titegroup and W231. The powders both did well.

I believed you would want magnum primers if you were to use slower powders as AA #9 or 2400.

Click to expand...

I've been using AA#9 for years as my "full magnum" load and have always used SPP. It provides me with all the bang I'll ever need or want in a .357 mag. Have never had a failure to fire.

SP primers are perfect. You can use SPM's in a pinch.

CraigC said:

Exactly!

Far as I know, the WSP and WSPM are the same primer in different packaging.

Click to expand...

Packaging WSP/WSPM, different internal component color so I'm assuming different primer.

Also, small rifle primers can be substituted for mag primers if needed.

Alliant, manufacturer of 2400 recommends against the use of magnum primers with 2400 and claims that standard primers give more consistent ignition.

Click to expand...

Buck, thanks! Hadn't seen that one.

2zulu1 said:

Packaging WSP/WSPM, different internal component color so I'm assuming different primer.

Also, small rifle primers can be substituted for mag primers if needed.

Click to expand...

I'm not sure about that one.. I think they are different heights

Small pistol and small rifle are the same diameter and height. Large rifle are about .007 inch taller than large pistol. I have no specific knowledge of the relative energies of small pistol magnum and small rifle.

Yesterday at the range I fired a bunch of .357 mag rounds loaded with 125 grain hollowpoints and about 16 grains of 2400. Winchester small pistol primers (not magnum) lit all of them very nicely out of my 686.

2zulu1 said:

Also, small rifle primers can be substituted for mag primers if needed.

Click to expand...

Yes, they can but proper load reduction and work up is called for. Probably not a big deal w/ light loads. But if you are at or close to max you need to work it back up properly. I don't own and SPM primers and use SR exclusively. But they were worked up and all the firing pins are strong enough to set them off.

Just for fun, a chart of CCI primer energies, may be a few years old.

As others have already said most powders for 357 use SP primers. The reloading data that you are using will indicate what primer is to be used.

All I've ever used with unique and 2400- last 41 years!

In ~45 years of hand loading, I don't think I've ever used a magnum small pistol primer in a .357 load. Haven't had a problem so far.

Edit: I'm looking at trying some loads that call for them too, but there are none around here anyway, so I'll be using standard SP primers. I don't anticipate problems.

Several of loads listed on Hodgdon's site show Winchester SPM primers for their loads. Alliant does list CCI 500 for 2400 & Bullseye loads.

I loaded some 2400 @ 12 gr. with magnum primers and a
158 gr. SWC. Think I'll do the same with SPP's and see if I can tell a difference.

PO2 --Interesting chart you posted. A few years back during the first big primer shortage I was unable to get SPP's and had to use CCI SR's. Using a chronograph I noticed little to any difference with faster pistol powders in the .38/.357. One benefit of the shortage was that I found that the CCI SR primers did a much better job with my magnum loads of 296 and WC820. I went from SD's in the mid 20's to single digit SD's and a corresponding accuracy improvement. My experience with 2400 in the .357 is standard SPP's work just fine and for me give better internal ballistics.