Using wrong primers (SP where SR is needed, etc). What happens?

Pistol primers are i think about 10 thousands shorter then rifle. So when fired they will move back and not seat properly. You can use magnum primers but should reduce the load.

Small pistol and small rifle primers are the same size.

Large rifle primers are taller than large pistol primers.

In general, pistol primers are not designed to withstand the higher pressure of rifle cartridges, so using pistol primers in rifle cartridges can be hazardous and produce pierced primers.

Some folks use small rifle primers in their handgun rounds, like 9 Major and 38 Super when loaded above normal SAAMI specs.

Rifle primers generally produce more spark (brisance) than pistol primers, so it's wise to work up pistol loads when using rifle primers.

Magnum primers generally produce more spark (brisance) than regular primers, so it's wise to work up loads when using magnum primers when standard primers were used for published load data.

A bud of mine did that. I was at the range with my chronograph and Jim wanted to chronograph some of his ammunition. Some of it was accidentally loaded with small pistol primers. His load was a 1/2 grain off max, he did not remember the exact charge weight. So, using his rifle, and one lot of my ammunition for comparison, we chronographed his loads.


DPMS Rifle Mod A-15 Jim’s rifle

20" 1:9 Chrome Lined barrel

My load:

69 Sierra 24.0 grains AA2520 BHA cases WSR (Brass) OAL 2.25"
22-Aug-04 T = 75° F

Ave Vel = 2865
Std Dev = 15
ES = 43
Low = 2850
High = 2893
N = 6


Jim's loads:


55 FMJ 24.0? grs IMR 3031 CCI Pistol Primers LC02
22-Aug-04 T = 75° F

Ave Vel = 3053
Std Dev = 45
ES = 150
Low = 2990
High = 3140
N = 10


55 FMJ 24.0? grs IMR 3031 CCI small rifle primers LC02
22-Aug-04 T = 75° F

Ave Vel = 3114
Std Dev = 49
ES = 142
Low = 3040
High = 3182
N = 10

All rounds went bang, there is a slight difference and real difference in velocity, the rifle primer being faster. I was very surprised that we did not experience any pierced primers. Now the 223 case is small capacity, and the pistol primer has a thin cup. Pistols do not have the robust ignition systems that rifles do, so the primers tend to be more sensitive. But what this data shows me, whatever primer compound that is in the pistol primer is probably the same stuff as in the rifle primer. Might be a difference, probably is a difference, but need more rounds down range, but the difference is small.

The real risk of this is having pierced primers, you don't want pierced pistol primers dishing your firing pin. CCI pistol primer cups are thicker than Winchester, if we had fired Winchester small pistol primers I am pretty sure each shot would have produced a pierced primer.

I do not recommend the practice of using pistol primers in rifle loads that are way above pistol pressures. I think it is realistic to state that small pistol primers are safe up to 357 Magnum pressures and not beyond.

Small pistol and small rifle are the same dimensions.

Large pistol are a bit shorter than large rifle.

Using small pistol primers in rifle cartridges can result in pierced primers. Using small rifle primers in pistols can result in failure to fire due to the slightly harder cup.

Magnum primers have more pop than non-magnum primers. They raise pressure on standard loads.

SP primers are rated for around 30k psi, where mag primers are around 35k psi. Rifle primers are rated for 60- 65k normally but there are some that run less.

Like said unless you want to cut up your bolt and FP I would not recommend using pistol primers in rifle loads. Now there are a few exceptions for rifle rounds like the 458 SOCOM it uses a LPM primer.

I have used Small Rifle in Handguns with no noticeable difference except as @Texas10mm replied, guns with light actions may have misfires.
I now use Magnum primers in all of my small pistol loads. A year or so back, I was running very low on Federal SPP and decided to try some magnums in target loads with Bullseye and Universal. The loads I tried were not maximum loads and the magnum primers made very little difference if any in velocity with the light loads and I saw zero signs of any pressure increase. Since Federal Magnum SPP were available at that time, I started stocking up and have since just gone to using the magnum primers for everything.

I work up all my loads with magnum primers, never had any trouble. I use large mag rifle primers in 45-70, small magnum pistol for 38 sp and large pistol mag in 45 colt. Reason being thats what i have and load more magnums than anything (454 casull & 357 mag). If you work up your load i have never seen any difference .

I try to use what's recommended, but there are exceptions. Years ago I bought a very nice new Winchester Model 70 in .300 WinMag. I could not get a load to shoot as well as I wanted out of that rifle. Someone suggested I try using a regular large rifle primer instead of the large rifle magnums primers I was using. I finally ended up with a sub-MOA load.

several years ago i started using mag primers in my pistol loads. i tested mag primers in 9mm, 40 s&w, 357 mga, 38 sp, 44 mag, and 45 acp. i load the test rounds with the normal powder, powder weight, and bullet. the mag primer was the only thing different. my test using my 1983 chronograph showed me that mag primers gave me between 25 fps to 50 fps more speed. no signs of high pressure or any other problems. later i did the same test with with large rifle mag primers in 30-06, 308, 30-30, and 7-08. don't remeber how much more fps i got with mag primers, but it was not much. so for me i use mag primers in small pisol and large rifle for all my loads. i know several that use small rifle in their 357 mag loads. i tried it but my marlin 1894cb would not set all them off on the first hit.

Walkalong said:

Some folks here did it during the craziness, some never quit.

Click to expand...

That could have been me. I started using Federal SPM primers several years ago when I couldn't find any standard Federal SP. Just like @frankmako above, I found just a slight increase in velocity and no pressure signs, so SPM are now used for all of my .38/.357 loads from 2.7gr Bullseye for target to Full House rounds with H110 and 2400. Now I only have to keep one type, and don't have to worry about whats in the tube when I go to load. One other small plus is on occasion you can find the Federal Magnums cheaper than standard and for the longest time, they were available and the standard were not. Haven't checked around lately. I have about 25k stoked up but still keep my eyes open for deals at gunshows.

after reading this i had to retest mag primer v. standard primers. so today while i was getting some time with the marlin 1894 cb in 357 mag. i had my current nra lever action silhouette pistol cartridge loads, 158 hp zero brand bullet, 6.5 grs of titegroup, mag primers, starline brass. i also had some test loads, 158 hp zero brand bullet, 6.5 grs of titegroup, standard primers, starline brass. got out the chronograph and shot some of both. the number is 19 fps faster for the mag primers. both loads shot the same using the same sight setting for all four animals.

https://www.shootingtimes.com/editorial/ammunition_st_mamotaip_200909/100079
Great read on primers.