SIGforum
Small Pistol/Small Rifle Primer Interchangeability and Primer Shortages. Particularly small pistol primer availability.

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/840601935/m/6130074874

January 09, 2021, 03:39 PM
cee_Kamp
Small Pistol/Small Rifle Primer Interchangeability and Primer Shortages. Particularly small pistol primer availability.
There have been several threads here on the Forum about using primers that were not the recommended type. Note that I am not talking about which company made them.

Re: Using small pistol primers (or small pistol magnum primers) when small rifle primers are required.

Personally, I would never do this potential combination as rifles generally run at considerably higher pressures compared to most handgun cartridges.
A perforated primer can cause firearm damage and/or personal injury.

Re: Using small rifle primers when small pistol primers (or small pistol magnum) are required.

I have shot countless thousands of rounds of .38 Lapua (.38 Super Rimless) in my Infinity IMM Open USPSA pistol. All of them using small rifle primers without any issues.
See the SAAMI drawing below. Small pistol & Small rifle primers and cartridge case head small pistol/small rifle primer pocket dimensions are identical.

If you are running maximum loads in your handgun cartridge, you may want to back off a bit and compare velocities if you switch to a different primer.
My testing shows minimal velocity change between small pistol primers and small pistol magnum primers. Pressure differences are unknown.
I see more velocity change switching between brands of primers than I see between small pistol and small pistol magnum primers of the same brand.

If you decide to use small rifle primers in your handgun cartridge, it's also smart to back off on your powder charge and work your way back up slowly.
Another item of concern, small rifle primers are considered "harder" than small pistol/small pistol magnum primers.
Be certain your particular handgun of choice has sufficient firing pin/striker energy to reliably ignite small rifle primers.
A hundred or two would be sufficient for the reliability testing I believe.

Go about your testing in a organized repeatable manner with safety being paramount. You'll be doing something reloading data/manuals/reloading instructors caution against doing.

NOTE: Large pistol and Large rifle primers and their respective primer pockets are dimensionally different and SHOULD NOT be interchanged.

So is the current small pistol primer shortage really so significant? Not really.

Primer_Primer Pocket Dimensions by cee_Kamp 32ACP, on Flickr



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NRA Instructor
USPSA Chief Range Officer
January 09, 2021, 04:10 PM
cee_Kamp
I set up my 9mm Luger cast lead reload using the recommended starting powder charge of Hodgdon CFE pistol powder (4.4 grains) and small pistol primers.
It's a 125 grain round nose locally hard cast projectile.
It easily makes USPSA Minor Power Factor. Checked with a chronograph it's about 130 PF.
In my case, since I'm at the recommended starting powder charge, and 0.6 grains below the maximum powder charge, I can use any small pistol/small pistol magnum/small rifle primer interchangeably without any load development or chronograph work at all.



NRA Benefactor Life Member
NRA Instructor
USPSA Chief Range Officer
January 10, 2021, 04:21 AM
sourdough44
I have looked into substitutes but haven’t tested yet.

To me, the logical starting point for evaluation is SR primers in mid-level pistol loads. I have watched a video or two on testing, that individual didn’t have any adverse issues.
January 17, 2021, 07:11 AM
vulrath
As I recall, CCI gave guidance that their small rifle magnum and regular small rifle primers are pretty much the same thing. Same cup thickness, diameter, cup material, compound, and amount of compound.

Folks have been rocking SR primers in pistol loads for a while, I'm told. Apparently competition shooters use them for more reliable ignition.


"In order to understand recursion, you must first learn the principle of recursion."
February 07, 2021, 08:41 AM
Flash-LB
Here's a scientific test done by Super Vel where they looked at Small Pistol primers, Small Pistol Magnum Primers and Small Rifle Primers with all other variables being identical.

He presents pressure and velocity and information regarding hardness of primer cups.


February 07, 2021, 02:21 PM
babue
quote:
Originally posted by Flash-LB:
Here's a scientific test done by Super Vel where they looked at Small Pistol primers, Small Pistol Magnum Primers and Small Rifle Primers with all other variables being identical.

He presents pressure and velocity and information regarding hardness of primer cups.

[FLASH_VIDEO]<iframe frameborder="0" height="315" src="https://www.youtube.com/embed/NGVRGsoOr6k" width="560"></iframe>[/FLASH_VIDEO]


Thanks for posting the Video. I have used all three and unscientifically gotten the same results. Just load and go.
February 07, 2021, 04:52 PM
sourdough44
Very informative video, hits all the areas of concern.
February 07, 2021, 05:04 PM
GT-40DOC
I enjoyed the video and what it showed.
March 12, 2021, 07:09 PM
PHC
Good info


Retired PHC USN