A little while back I picked up some Winchester Small Pistol Magnum primers since I couldn't locate and standards. I loaded up some test rounds, half with standard primers and half with magnums, same powder charges, same brass, same bullets. I didn't have any overpressure signs with any of them. Here were my results (I have purposely left out powder charge weights):

.32 S&W Long, 100 grain RNFP, Trail Boss:

Ave Std. Primer: 570fps, Std. Deviation 18.08
Ave Mag Primer: 553fps, Std. Deviation 8.13

.32 H&R Magnum, 100 grain RNFP, AA#5:

Ave Std. Primer: 749fps, Std. Deviation 32.98
Ave Mag Primer: 798fps, Std. Deviation 12.11

.38 Special, 158 grain RNL, HS-6:

Ave Std. Primer: 884fps, Std. Deviation 30.27
Ave Mag Primer: 890fps, Std. Deviation 20.86

9x19mm, 130 grain FMJ, HS-6:

Ave Std. Primer: 990fps, Std. Deviation 20.79
Ave Mag Primer: 1043fps, Std. Deviation 19.70

9x19mm, 125 grain RNL, HS-6:

Ave Std. Primer: 1116fps, Std. Deviation 17.54
Ave Mag Primer: 1122fps, Std, Deviation 13.20

The only two loads that the magnum primers made any significant difference in where the 100 grain H&R Magnum and the 130 grain FMJ 9x19mm. The magnum primers seemed to be more consistent overall, though it generally didn't represent a huge change. I tested the magnums with my standard loads and the conclusion I came to is that it is safe to use magnums in place of standards in the loads I generally use. I'd test other cartridges and charge weights before using magnums in those loadings.

I'm happy with the results and I plan to use my magnum primers for the cartridges above.

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Hello Cleveland, Rock and Roll

Great report Landric. As often as I've seen this question asked recently it ought to be a sticky.

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Andy

This is good information and leaving the powder weight is a good thing. One question though, where are you in relationship to maximum charges with these loads?

In the cartridges you list, it is doubtful that overpressure problems will occur. Change the cartridge to 40S&W though and problems could happen real fast.

For the cartridges you have listed though, as Andy has stated, this is good information. I hope no one extrapolates it to their cartridges without doing their own testing though.

FWIW

The .32 S&W Long and .32 H&R were in about the middle of the data I have.

The 9mm FMJ load was near, but not at, maximum. The 9mm LRN was using the same charge weight, but with the data I have for the slightly lighter bullet, it was a little further away from max than the FMJ load.

Given my experience with the magnum primers in the 9mm FMJ load, I'd probably reduce it a little bit if I decided to load batches. My goal with the 130 grain FMJ is right at 1000fps to safely make power factor for IDPA. As one can see, my standard primer load is right about there. The magnum primer load is a little higher. As I said, no pressure signs at the load I was using with the mag primer, but it looks like I could still make the velocity I am looking for with a slightly reduced charge. Since I'm just punching paper (and knocking down steel sometimes), there is no reason to load hotter than 1000fps.

There was no significant difference between the 9mm standard and 9mm mag using the LRN bullet. Obviously I could reduce either to an average of about 1050fps and still make power factor easily. However, the LRN has less felt recoil (and no leading problems) where it is, so I probably won't change anything there using either kind of primer.

Depending on who's data one looks at, I was either just below max or just into +P levels with the .38 Special loads I tested. Since testing was being done in a .357 Magnum L-frame, I wasn't too worried about possible high pressure. As it turned out with the .38 Special there was no significant difference in velocity and the magnum primers actually resulted in more consistent results. Neither showed signs of excessive pressure. I've shot many thousands of the same load using standard primers without any problems. The change to magnum primers seems to have improved the load, and I might well stick with magnum primers for it once the general component madness reseeds.

I don't care for the .40 S&W, nor do I care to handload it, primarily due to the small case/high pressure/heavy bullet combination one encounters there. It would be an interesting test, though I would have reduced loads more significantly given the .40's characteristics.

I tested every cartridge I load that uses a small pistol primer with magnums (except the .357 since I didn't think there was new knowledge to be gained using magnum primers to set off heavy .357 powder charges). Overall, I didn't find any reason not to use magnum primers with my loads. If I end up loading batches of FMJ 9mm, I'll probably reduce the charge weight. I have plenty loaded with standard primers and still have some standard primers also though, so that might never be necessary. I think I'll stick with magnum primers in my .38 Special loads.

All in all, it was educational (and I had fun doing it).

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Hello Cleveland, Rock and Roll