small mag pistol primers
- Thread starter gsfxst
- Start date
Nice test. No significant difference in pressure generation, but differences in cup metal alloy, small pistol being the softest, rifle being the hardest. I have long heard this, nice to see proof from one of the manufacturers.
For conventional small capacity, reasonably high load density handgun rounds I agree there is virtually no difference between small primers beyond potential light strike issues (with the exception of magnum rifle primers). However, in terms of light strike issues there can be differences even between brands.
For example one of my S&W revolvers has a marginal hammer spring that is 100% reliable with CCI 500 primers but has occasional light strikes with Winchester WSP primers.
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Where primer brisance starts to matter is in rifle rounds, in terms of accuracy and to some extent safety, and potentially in some of the older high capacity low load density cartridges, like the .38 Special
For example the .22 Hornet in general is an exceptionally accurate round, but many .22 Hornet shooters get even better accuracy with small standard pistol primers. It makes sense, as the case capacity is quite small, and the pressure is low enough that the lighter cup doesn’t pose any issues.
At the same time, I’ve measured average velocities and higher standard deviation in velocities using magnum small rifle primers in the .22 Hornet - on the order of 75 FPS faster with some loads and with some obvious pressure signs. In that particular instance with some powders it makes a significant difference. Enough that if I do another batch of .22 Hornet using small rifle primers, I’ll take the precaution of working up a load to my target velocity using the rifle primers.
At the other end of the spectrum, large capacity rifle cases using some of the harder to ignite powders really do need a magnum primer for consistent ignition and to avoid hang fires.
Accuracy wise, primer brisance also effects how much the powder is scattered in low density loads and too much primer with a low load density can create pressure spikes.
That increased scattering of powder in high volume cases like the .38 Special (which was originally designed as a black powder case and has way more volume than it needs for smokeless powder). Excessive primer brisance can potentially create pressure spikes with the very low load density loads you often have with some of the fast flake powders.
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The point here is don’t over generalize the results in 9mm cartridges to and other pistol rounds to the entire range of rifle rounds or think you can use a magnum small rifle primer, or a large rifle primer of any type.
(See my post on Supervel’s BYOP program below.)
For example one of my S&W revolvers has a marginal hammer spring that is 100% reliable with CCI 500 primers but has occasional light strikes with Winchester WSP primers.
——
Where primer brisance starts to matter is in rifle rounds, in terms of accuracy and to some extent safety, and potentially in some of the older high capacity low load density cartridges, like the .38 Special
For example the .22 Hornet in general is an exceptionally accurate round, but many .22 Hornet shooters get even better accuracy with small standard pistol primers. It makes sense, as the case capacity is quite small, and the pressure is low enough that the lighter cup doesn’t pose any issues.
At the same time, I’ve measured average velocities and higher standard deviation in velocities using magnum small rifle primers in the .22 Hornet - on the order of 75 FPS faster with some loads and with some obvious pressure signs. In that particular instance with some powders it makes a significant difference. Enough that if I do another batch of .22 Hornet using small rifle primers, I’ll take the precaution of working up a load to my target velocity using the rifle primers.
At the other end of the spectrum, large capacity rifle cases using some of the harder to ignite powders really do need a magnum primer for consistent ignition and to avoid hang fires.
Accuracy wise, primer brisance also effects how much the powder is scattered in low density loads and too much primer with a low load density can create pressure spikes.
That increased scattering of powder in high volume cases like the .38 Special (which was originally designed as a black powder case and has way more volume than it needs for smokeless powder). Excessive primer brisance can potentially create pressure spikes with the very low load density loads you often have with some of the fast flake powders.
——-
The point here is don’t over generalize the results in 9mm cartridges to and other pistol rounds to the entire range of rifle rounds or think you can use a magnum small rifle primer, or a large rifle primer of any type.
(See my post on Supervel’s BYOP program below.)
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I have not heard of CCIs BYOP program. Can you share a link?
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Supervel has a BYOP program although it has some important limits you need to understand before you start mixing and matching primers.
The BYOP program is limited to certain pistol cartridges:
- 9mm 115 gr FMJ;
- 9mm 124 gr FMJ;
- 9mm 147 gr;
- .40 S&W 180 gr FMJ; and
- .45 ACP 230 gr FMJ.
Also bear in mind the primers they allow are:
- small pistol;
- small magnum pistol; or
- small rifle.
For .45 ACP they only allow large pistol or magnum pistol primers - no rifle primers.
They *do not* allow small magnum rifle primers, nor the NATO equivalent in the 9mm or .40 S&W or large rifle in the .45 ACP.
Finally, they limit primers to the following brands:
-CCI,
-Federal,
- Remington,
- GINEX,
- GENEX,
- Magtech,
- FIOCCHI,
- Murom, or
- Sellier and Bellot.
——
In short, they swap primers for selected loads in reasonably small capacity, high load density cartridges using a powder or powders that are not primer sensitive, with strict limits primer types and brands.
BYOP Program
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Interesting video. It pretty much confirms my suspicions, but it’s more of a demonstration than a real scientific test.
I have never understood calling 231 a ball powder. It looks nothing like, for example, AA5 or Ball C2, or any other powder I normally think of as a ball powder. If it’s a “flattened” ball, then isn’t it, for ignition purposes, really no longer a ball? Well anyway, I remain with the “no need of a magnum primer with 231” camp. My chronograph has never shown any improvement in ES or SD with magnum primers, and in some cases has shown the opposite, so what few I have are getting old and don’t get used.
I recently tried something similar with my .300 Weatherby and Reloader 25 powder. It’s a big charge of very slow burning powder in a long, thin case. I used Federal 215s and standard Winchester large rifle primers (not the ones marked for “standard or magnum” loads). I have no pressure measuring equipment and I don’t have the chronograph readings or targets handy right now, but I saw very little difference in ES and SD, and accuracy at 100 yards. I only fired 3 rounds of each, so, again, not much of a test. Temperature was about 85 degrees F.
These very limited tests, like mine and the one in the video, really don’t stand up to much scrutiny. But they are what they are.
I have never understood calling 231 a ball powder. It looks nothing like, for example, AA5 or Ball C2, or any other powder I normally think of as a ball powder. If it’s a “flattened” ball, then isn’t it, for ignition purposes, really no longer a ball? Well anyway, I remain with the “no need of a magnum primer with 231” camp. My chronograph has never shown any improvement in ES or SD with magnum primers, and in some cases has shown the opposite, so what few I have are getting old and don’t get used.
I recently tried something similar with my .300 Weatherby and Reloader 25 powder. It’s a big charge of very slow burning powder in a long, thin case. I used Federal 215s and standard Winchester large rifle primers (not the ones marked for “standard or magnum” loads). I have no pressure measuring equipment and I don’t have the chronograph readings or targets handy right now, but I saw very little difference in ES and SD, and accuracy at 100 yards. I only fired 3 rounds of each, so, again, not much of a test. Temperature was about 85 degrees F.
These very limited tests, like mine and the one in the video, really don’t stand up to much scrutiny. But they are what they are.
