Small Pistol Magnum Primers?

M

Marco Califo

New member
I am seeing SP Magnum primers available. Question is can I substitute these for regular SP and adjust powder down say 5%?
This is for 9mm and 40 SW.
 
Yes however; the cups maybe also be a bit thicker than standard primers. This can occasionally give you miss fires depending on what you shootings through. I have experienced some miss fires using CCI small pistol mag primers in .38spl with my Chief Special and Police Positive.
 
Go for it. just seat them very firmly to maximize sensitivity. If you have a chronograph, check velocity for charge adjustment purposes. In some instances, the magnum primer will actually produce lower velocity because it is unseating the bullet before the powder has burned enough to do it.
 
With regular loads with fast powders you probably won't see much difference. They are needed for slow powders like H110 but not a problem with 231. I don't know if they would cause high pressure with bullseye or clays which are about the fastest pistol powders out there. With Unique I bet the difference would be too small to measure.
 
Unclenick said:
Go for it. just seat them very firmly to maximize sensitivity. If you have a chronograph, check velocity for charge adjustment purposes. In some instances, the magnum primer will actually produce lower velocity because it is unseating the bullet before the powder has burned enough to do it.
Click to expand...
Unclenick,

Would a heavier crimp mitigate this?
 
Usually you see a little increase in velocity.

For example some back to back tests:

Longshot in .44 Mag.
10.0gr Longshot, 240gr SWC, CCI-300, 1099fps, 65 ES, 14 shots
10.0gr Longshot, 240gr SWC, CCI-350, 1148fps, 49 ES, 15 shots

Unique in .45 Colt
8.5gr Unique, 255gr SWC, CCI-300, 977fps, 56 ES, 15 shots
8.5gr Unique, 255gr SWC, CCI-350, 985fps, 82 ES, 15 shots

BE-86 in .45 Colt
8.0gr BE-86, 250gr RNFP, CCI-300, 886fps, 28 ES, 15 shots
8.0gr BE-86, 250gr RNFP, CCI-350, 908fps, 27 ES, 15 shots

But then there are cases where the magnum primer caused 'less' velocity. Ran into that with high end of trailboss too...

2400 in .357
13.5gr 2400, 158gr SWC, CCI-500, 1270fps, 49 ES, 15 shots
13.5gr 2400, 158gr SWC, CCI-550, 1263fps, 53 ES, 15 shots

And so it goes.

I did quite a few powder back to back tests to assure my self that I could substitute in a pinch.
 
In the long revolver cases you are less likely to see the magnums work backward. In the short powder space pistol cases, the bullet unseating phenomenon becomes more common. Also, the revolver cartridges usually have solid roll crimps which, to answer Akinswi's question, can help fight unseating of the bullet. But rimless short pistol cartridges typically get a taper crimp, and a taper crimp dug into a lead bullet has the profile of a ratchet tooth, and it stops recoil and feed ramping from pushing the bullet deeper into the case but doesn't offer nearly as much resistance to bullet pull as a roll crimp does. All this works to make it easier for the primer to make little or even reversed velocity effect in pistol rounds.

There is a YouTube video of a fellow with a pressure and velocity gun testing the CCI 500/550 combo in 9 mm and seeing, IIRC, no discernable difference. It would be interesting to do the same with 300/350 in the 45 Auto. I have a pressure barrel for 45 Auto, but no current production 300/350s. When they become available, I'll give it a try.
 
By the time I decided to order the CCI SPM, and use them as SP, they were out of stock again at Midsouth. I have seen them in stock a couple of times. Now that I know I can use them, I will scoop some up next time. CCI primers are going for $85 - $89 at Midsouth, when they have them.
 
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