Small Pistol Magnum Primers - Substitute for Small Pistol Standard??

[Larry Gibson]

......I don't know what to think about the result you got with the VV powder. jd

As mentioned, a given amount of a powder will produce only so much energy regardless of how it is ignited. In a pistol or rifle barrel the difference is in the "quickness" of the ignition. It is also greatly influenced by the expansion ration. In pistol cases with the faster burning powders they are ignited and burn very quickly so there is not much difference regardless of the ignition. However, with slower burning powders such as with HS6 and the VV powders we begin to see the difference in ignition between the primers. The milder the primer the slower the ignition and burn is so the bullet moves further into the bore which increases the volume for the expanding gas to fill, thus the time pressure curve is slower with a slightly less max psi. With the "hotter" primers the ingnition is more intense resulting in the fast time/pressure curve and a slightly higher max psi.

[Larry Gibson]

I guess I am not nearly as scientific as some, but I use either SP or SPM primers interchangeably with NO noticeable difference in performance. I load the same powder and the same bullet and use whatever primer is available. I prefer to use SP, but if SPM primers are all I can find, that is what I use.

With the components you are using you may very well not find any "noticeable" difference. However, if you change the components other than the primer type then the "difference" may become "noticeable".....perhaps very "noticeable"......

[Pops1911]

I read an interesting article a while back that showed fixed load data for pistols that interchanged SP, SPM, SR, and SRM and there was not any appreciable difference in pressures or velocities. My primary round is the 9mm that I load with a 124 gr Hi-Tek bullet and the max load of N320. I have interchanged SP and SPM primers as available and never have noticed any difference in performance. These are a standard load that I shoot many different guns and seated for the shortest chamber which has been the Glock.

[sureYnot]

I read an interesting article a while back that showed fixed load data for pistols that interchanged SP, SPM, SR, and SRM and there was not any appreciable difference in pressures or velocities. My primary round is the 9mm that I load with a 124 gr Hi-Tek bullet and the max load of N320. I have interchanged SP and SPM primers as available and never have noticed any difference in performance. These are a standard load that I shoot many different guns and seated for the shortest chamber which has been the Glock.

As indicated by Mr. Gibson, there's little effect with the fast powders. That's why it's a non-issue with pistols such as 9mm. It's the slower (in this case, magnum) powders that suffer this effect.

[Hick]

I guess I am not nearly as scientific as some, but I use either SP or SPM primers interchangeably with NO noticeable difference in performance. I load the same powder and the same bullet and use whatever primer is available. I prefer to use SP, but if SPM primers are all I can find, that is what I use.

I do essentially the same. Worth noting, however, that I am not advocating changing the primers without being cautious. Larry gives us great info here. It just happens that I don't like hot loads and virtually all my favorite loads are the starting loads from the manuals-- 38 Special, 357 Magnum, 9mm, 44-40, 455 Webley, etc. At that low end you can get away with changing primers more readily.

[Hanshi]

I've used small and small pistol magnum primers interchangeably for decades; but I've also done the same thing with large pistol & magnum pistol primers. My primary shooting and reloading has involved the .38 spl and the .45 acp; target loads using Bullseye and Unique. Service, heavy and hunting loads received different treatment but represented only about 25% of my reloading. Never experienced any problems or unanticipated results.

[sureYnot]

I've used small and small pistol magnum primers interchangeably for decades; but I've also done the same thing with large pistol & magnum pistol primers. My primary shooting and reloading has involved the .38 spl and the .45 acp; target loads using Bullseye and Unique. Service, heavy and hunting loads received different treatment but represented only about 25% of my reloading. Never experienced any problems or unanticipated results.

Because those are fast powders.

[racepres]

I do essentially the same. Worth noting, however, that I am not advocating changing the primers without being cautious. Larry gives us great info here. It just happens that I don't like hot loads and virtually all my favorite loads are the starting loads from the manuals-- 38 Special, 357 Magnum, 9mm, 44-40, 455 Webley, etc. At that low end you can get away with changing primers more readily.

In This....I believe!!!

[Kai]

I have no problem using SPM primers in mostly everything except the 32 ACP.

What happens when you use them in 32acp that is unacceptable?

[cpaspr]

I read both this thread, and the earlier one Larry referenced in post #17. I'm curious about going a direction that didn't seem to be addressed. I'm planning on loading a Lyman 358429 Keith SWC at 173gr in .357 brass ahead of H110 powder, for use in a Marlin 1894 rifle. I have SP and SR primers, but not SPM. Can SR primers be substituted for SPM?

One thing I find interesting. Hodgdon's reloading data indicates the same components: Winchester SPM primers; Sierra 170gr JHC bullet; starting load of 14.0gr (pressure 25,900 CUP) and max load of 15.5gr (pressure 40,800 CUP)of H110; same twist rate of 1-18.75". The velocities though, surprised me. Out of a handgun (10" barrel), the velocities are 1328 to 1497. From an 18.5" rifle barrel, the velocities are 1537 to 1662. My .357 handguns have a max barrel length of 4". This tells me there's a lot of velocity potential getting lost beyond that 4" max barrel length if I use H110 in the handgun.

[Larry Gibson]

Question; will your 4" barreled revolvers(?) reliably fire the SR primers in DA mode?

If the answer is yes, then you could substitute the SR primers and work the up a load. My experience with top end magnum level accurate revolver loads with PB'd cast bullets when fired in rifles when the velocity gets above 1450 fps +/- the accuracy is nothing to write home to mamma about. [Note; that is with normal lubed bullets. PC'd bullets may give different results.] It's why I recommend working up the load for accuracy in the rifle, using pistol data, and then just accepting the load for use in the revolver. It is also the reason I prefer to use a GC'd cast bullet for top end magnum level loads because they are accurate at higher velocities in the rifle.

Yes, you will probably lose 500+/- fps with the same load using H110 and the 358429 in the 4" revolver.

[dale2242]

I did a very unscientific test of LP vs LPM primers in 45ACP with 5 gr of Bullseye powder and Lyman 452460 bullet.
I fired 10 of each load through 2 different 45s.
One was an Ithica issue 1911 and the other a Sig P220.
I shot all loads for accuracy and over my Chrony for velocity.
I found very little difference in velocity or accuracy.
Your mileage may vary.

[cpaspr]

Ah, yes. Good point on the cast boolits w/o gas checks, Larry. I took your advice on .308 x 110gr in the .30 Carbine. Those wear gas checks and work just fine. Hmm. May need to look into getting a gas checked mold for .357s.