Substituting SP Magnum primers.....

[SmithNut]

Since I (and I'm guessing others) have a good/better supply of Small Pistol Magnum primers (and running out of regular Small Pistol primers) here's a question for the group.

If loading for 9MM, 40 S&W and .38 Special, is there a rule of thumb about reducing established loading data when using Magnum primers? I'm primarily using TiteGroup and CFE at this time. Would someone reduce the power by say 10% or are there other ideas...

I'm not against experimenting, but just don't want to over pressure using the Magnum primers.

Thanks, in advance

 

[stansdds]

I doubt there is going to be a huge difference. To be absolutely safe, especially if your current loads are at or near maximum safe pressure, you could back off about 5% and work up to your desired velocity and pressure.

 

[mikld]

Not complaining, but for the numerous future questions on primer substitutions, is a sticky is needed? I see "can I use XXX primers in place of YYY primers?" almost daily in the forums I visit...

Normal "Reloading 101" is to do another load work up when any component is changed...

 

[BigMoneyGrip]

I doubt you'd see any difference unless you were loading to the max. I've used magnums in 9mm and they were fine. The chrono showed no difference in velocity but the SD was in the single digits. These were loaded very soft, though.

 

[DWalt]

This and similar questions are probably the most often posted here, and the answer is always the same, essentially that small rifle and small pistol magnum primers (which are identical) can be safely substituted for small pistol primers in handguns without significant performance effect using identical loadings. The only caution is that because SR and SPM primers have thicker cups and are less impact sensitive than SPPs, you should first test them in your gun to be certain of 100% ignition reliability prior to loading large quantities of ammunition. This is best done by priming at least ten empty cases. If all of them fire, you are probably good to go for that gun.

 

[SmithNut]

I doubt there is going to be a huge difference. To be absolutely safe, especially if your current loads are at or near maximum safe pressure, you could back off about 5% and work up to your desired velocity and pressure.

I doubt you'd see any difference unless you were loading to the max. I've used magnums in 9mm and they were fine. The chrono showed no difference in velocity but the SD was in the single digits. These were loaded very soft, though.

This and similar questions are probably the most often posted here, and the answer is always the same, essentially that small rifle and small pistol magnum primers (which are identical) can be safely substituted for small pistol primers in handguns without significant performance effect using identical loadings. The only caution is that because SR and SPM primers have thicker cups and are less impact sensitive than SPPs, you should first test them in your gun to be certain of 100% ignition reliability prior to loading large quantities of ammunition. This is best done by priming at least ten empty cases. If all of them fire, you are probably good to go for that gun.

Thanks for the informative responses....

Appreciate you taking the time for someone who doesn't frequent in this forum....

 

[TAROMAN]

I substituted Fed SP MAG for FED SP in my 9mm steel challenge load.
Chronographing it surprised me:
Higher Vmin, lower Vmax and smaller ES and lower SD.
Not a huge difference, but interesting nevertheless.
Since then I have used whichever is available with no ill effects.
My experience, YMMV.

 

[Nevada Ed]

In my 38 , 357 and 9mm loads

from the regular to magnum primer, I only had to change the powder by
.2 grains to be in the ball park, with my loads, per my chrony.

I did notice that "MY" revolvers got lower fps with the federal SPP primers, than the other types, that I used.

If I had just one primer to use for pistol/revolver, it would be the Win. spp.

 

[38SPL HV]

When changing primers and bullet from published load data, I usually begin from the start load and work up again while checking velocity over the chronograph. I do obtain slightly tighter extremes using magnum primers in lieu of standard primers from the same manufacturer particularly with some powder types but statistically they’re not very significant. Of course we have other variables, powder types, bullet material (cast vs swaged, vs jacketed) along with OAL…bottom line pay attention to your published load data and when changing components start again from the minimum load specified and work up…conservative approach but safe.

(Also note that load data will specify magnum primers for some powder types; particularly, in 357/41/44 Magnums…don’t deviate from these and use the magnum primer as specified).

 

[ArchAngelCD]

I agree you will see very little difference in the loads when using Mag primers. Of course when changing any component in a cartridge you should drop back and work up again. That rule is not magnum primer specific.

Like mentioned above, many times the magnum primer will improve your SD and ES numbers with some exceptions of course.

You will not blow your gun when using a SPMP instead of a SPP. You might see a change of .1gr to .2gr at most to achieve the same velocities.

 

[BLUEDOT37]

LabRadar comparision using SPP -vs- SRPs

Comparing SPP to SRPs, using three different powders, the average fps across a range of powder weights was only a handful of fps difference in most cases.

Reduce your powder charge by a tenth or two if you like but if they can be ignited reliably in your handgun then there shouldn't be a problem.

.



.

 

[mmb617]

I load 9mm with TiteGroup and .45 ACP with CFE. I don't load either close to maximum loads so I consider standard and magnum primers to be interchangeable. I can't imagine it makes a difference unless you are really pushing the max, and maybe not even then.

 

[38SPL HV]

Comparing SPP to SRPs with several different powders the average fps across a range of powder weights was only a handful of fps difference in most cases.

Reduce your powder charge by a tenth or two if you like but if they can be ignited reliably in your handgun then there shouldn't be a problem.

.



.

Excellent data…proves in your tests that they’re pretty much statistically the same

 

[len917]

Found no difference with small mag pistol primers on .38 spec or 9mm
Use what you can get

 

[BB4XL]

The only problem that I encountered was that 38 spls in J frames would sometime get light hits and would not fire. I have a 638 that has a Wolff extra power 8lb hammer spring and this also had some misfires. In all I have 3 J frames that this happens in. These revolvers work fine with standard small pistol primers. The SPM also worked fine in K and L frames.

Also used in 9mm and .40s in several different pistols including Glocks, Hks Sigs and Brownings. No problems at all. These were Winchester small pistol Magnum primers.

 

[DWalt]

I have a few handguns that I have found to be unreliable with SRPs. Never had any problems with larger frame Ruger, Colt, and S&W revolvers. I have one small semiauto 9mm which is very unreliable, maybe half or more won’t fire on the first strike. But it’s OK with factory loads and handloads using SPPs.

That is why I recommend first popping at least ten SR primers (more is better) with no FTFs in your handgun before using them to load up 500 rounds.

 

[rsrocket1]

That is why I recommend first popping at least ten SR primers (more is better) with no FTFs in your handgun before using them to load up 500 rounds.

I did that when I first started using CCI 400 SRP's in pistol loads. I used my Ruger Service Six and all 6 fired perfectly. That was in the day of 2.5 cent primers. I now have no hesitation to buy SRP's or SRM's if I am short of SPP's.

Small rifle primers are probably the most versatile primers around because I can use them in pistols and rifles while I will still not use SPP's in 55,000 psi rifle loads. I've heard of precautions of SRP's not igniting with weak springed revolvers but I only shoot stock hammer/striker spring guns so it hasn't been a problem for me.

 

[DWalt]

Statistically, 10 of 10 fires is a much more reliable indicator than 6 of 6 fires. 20 of 20 fires is very, very close to 100% reliable.

Back when I was doing statistical go-no go testing of this nature we considered 20 of 20 (positives or negatives) to constitute effectively 100% confidence. Samples of more than 20 were considered excessive. But 10 of 10 is pretty good, mid- 90s%. 6 of 6 is somewhere in the 80% confidence range. There are binomial expansion tables available which provide such reliability estimate information.