Winchester Magnum Small Pistol Primers

[MustangGreg66]

Well, I bought a bunch of primers at the last gun show and without realizing it, I got a sleeve of Magnum small pistol primers instead of normal SP. Most of my shooting is .40 minor for production division... I'm wondering if these magnum primers would be ok to use, or are they possibly going to have a harder primer cup and not seal as well with minor loads? What is the purpose of magnum SP primers? Is there a particular caliber they're intended for or?

Thanks

[al503]

I usually use pistol for minor and rifle for major loads. However, I've tried these for 9 and .40 major/minor loads with no issues. The only thing I wouldn't use them with is loading short with Clays in .40 or 9 major with anything but a very slow powder.

Edited April 3, 2009 by al503

[MustangGreg66]

Hm, my load is usually 3.3gr of Clays under a 180gr bullet seated to 1.135 OAL I'm not sure if this qualifies as "short" in your book since it's the max most of the books state.

I guess to be safe I should re-develop the load, start a 3.0 and work up over the chrono...

I'm still wondering what the intended purpose of small pistol magnum primers are.

[Sean Gaines]

I use small magnum primers in my 38 super, works fine

[Rocket35]

Unfortunately I have to resort to use them in .40 major. I loaded a couple test rounds using Alliant E3 powder at OAL 1.180". I will report back on the progress or mishaps!

Edited April 5, 2009 by Rocket35

[Toolguy]

Small pistol magnum primers are for slower powders in .357 mag, .357 max, .357 Sig, etc. They can be used for

lower pressure loads, assuming proper load workup. .38 Special is pretty safe in a .357 gun, but .40 S&W and

9mm major are a lot more likely to have pressure spikes that can blow up your gun. Proceed with great caution

anytime you make up a load that isn't in a lab tested loading manual. Changing any detail of a load can be

unpredictable.

[Albertl35]

I have loaded 9mm minor, 40 SW major, 45 major and 38 Super comp major with Fed small pistol magnum primers and they work fine. They are a littel flattened on the 38 super comp laoded to 168 PF. I will be switching the 38 SC to small rifle primers. Everthing else will be on small pistol primers till I run out.

[joecichlid]

Warren, thanks for the info. I am running into the issue of lack of primers for my Super and have thought about trying Magnum primers but with your info I am having second thoughts. I am running Hodgdon Longshot powder which according to Hodgdon's burn rate chart is just a shade faster buring than Lil Gun and H-110 which from what I remember are powders that normally are used with magnum primers, please correct me if I am wrong. Think it would be a huge issue?

Joe W.

[MustangGreg66]

Thanks for the info guys. My dad has some .357s but he has a stockpile of ammo so I doubt he'd want to load 5k with small magnum primers... maybe I'll have to try to trade them at the range...

[open17]

When I was loading minor 40 for production, I got a sleeve of WSPM by mistake. They

will increase your fps by maybe 10. Back off a little on the powder and work back

up if you are out on the bleeding edge of pressure.

I was loading a light load of N310 with 180 gr bullets, and saw my extreme velocity

spread tighten up from 40 fps to 10 fps with the magnum primers. No downside

that I know of---I now use WSPM for 9 minor and major, 40 minor and major,

and the occasional 38 spl or 357 load.

[Rocket35]

Here were my results using a Competition Electronics Prochrono:

Weather: Sunny, calm winds and 42 degrees

Gun Information

Gun STI Custom

Barrel Schuemann 6"

Load Information

Powder Alliant E3

Primer Magtec Magnum

OAL 1.180"

Crimp .410"

Bullet Information

Weight 220 grains

Mfr. S&S Casting

Shape Tunicated- lead

P.Chg 3.0gr

Shot 1 753

Shot 2 767

Shot 3 755

Shot 4 782

Shot 5 749

Shot 6 745

Shot 7 760

Shot 8 810

Shot 9 755

Shot 10 786

High 810

Low 745

Average 766.00

Std. Dev 20

P. Factor 168.52

I need to work on better Std Deviation with more consistancy at the press. But looks to be about the same power factor with 3.0gr of powder with both Standard and Magnum primers. All rounds fired reliably and no pressure signs. I tested 40 rounds in 10 round lots at 3.0gr, 2.9gr, 2.8gr and 2.7gr loadings.

Edited April 6, 2009 by Rocket35