I have small supply of Small Pistol Primers, Small Magnum Pistol Primers and Small Rifle primers. Are these primers interchangeable and what are the basic functional differences?

Thanks, Mick

They are all the same diameter. the pistol and rifle primers are slightly different lengths. They all have different "Flash" characteristics of powder and duration.

Are they interchangeable? Sometimes. Some rifle's firing pin won't reach a pistol primer. The load for each type of primer in the same cartridge should be developed from scratch. The same amount of same powder with a different primer will most likely have a different velocity, and probably group differently.

Personally, in some target loads for Black Powder, I use large pistol primers instead of large rifle. The rifle primer's massive power expelles the powder down the barrel before it is all ignited. The pistol primer keeps the length of the combustion shorter and more consistent. Will this matter in your gun and ammo? Only one way to find out!

Ivan

I have reloaded ammo that requires spp's with srp's 3 out of 5 don't fire in my s&w mp 40 the .9m same in my sig 226 however the .38/.357 's fire in my model 27 and the 9mm's fire in my 986 5" with no problems
the semi autos don't have enough force to detonate the primer make a light depression because the rifle primers are harder.

There are only TWO kinds of primers.......the ones you have and the ones you shot.

Use what you already have.

Randy

This link is a Primer on "primers"! lots of detail and should answer all your questions about primers.

Primer Info & Chart + Milspec Primers for Semi-Autos & Other Primer Applications

Smiles,

Small primers are all the same, dimensionally. Large rifle primers are .008" taller than large pistol primers. Small pistol primer interchangeability; The Handloaders Bench

Dimensionally, SPPs and SRPs, whether standard or magnum should be expected to have the same external dimensions. The metal of the cup in magnum and rifle primers may be expected to be harder (stronger) and standard primers present a slightly less powerful flash since more power is sometimes needed to ignite larger amounts and slower burning powders in magnum loads. In some variants between manufacturers, rifle primers may be a little “hotter” than pistol primers as well.

As for practical interchangeability, fit should be no problem and unless the cup hardness becomes a factor (think fine tuned revolvers with soft mainsprings) they should all work. But if you are making loads up on the hairy edge of acceptable maximum power, the extra boost they get from hotter (magnum) primers may produce dangerous pressures. For target loads your main concern will be changes in accuracy due to altering your burb rate.

This in a nutshell is the answer to your question, retnavyshooter. I hope it helps. BTW were you shooting a 45 Hardball Gun, or one of the new 9s for the third leg?

very true what I am reading here:

The primers that you own are the ones you are going to be shooting.

This doesn't exactly answer your question, but here's some related information from some limited chrono testing of different mfg'd primers that I did a few years ago.

Fired with 9mm 124gr, 5.2 gr AA5, mixed cases, fired from a Spr.1911 A1 5":

Win SPP: 950 fps
S&B SPP: 910 fps
Fed.Match SPP: 930 fps
CCI-Mag SPP: 930 fps

It appears to me that there was more difference between mfg's formulations than from between standard and mag primers. But again, this was from limited testing; from between 10 and 30 rounds fired from each sampled mfg. -S2

Green Frog: Only have 18 points toward Distinguished Pistol. Always shot .45 hardball. Don't compete anymore, arthritic hands don't work well for one hand hold. I had a Navy 7.62 M1 Garand when I Distinguished Rifle.

Just shoot for pleasure now, competition days are over.

This is an interesting question, and when I first started reloading years ago was told not to mix primers. I think you could get away with it without much of an issue, but I would only consider the lightest powder charges if I resorted to this.

A dear friend of mine, dead these 20+ years now was a gunsmith for the Navy team back in the late '50s. He ended up with bad arthritis too, but still loved to shoot. He was inactive for about 25 years then started shooting in our casual Bullseye league and on a bad day shot better than I ever could. His hand just sorta fit a 45 grip naturally, and he used a Model 41 with the Herrett grips that gave it that "45 shape" to shoot his 22 events.

He built two 45s for me, a tuned 70 Series Gold Cup for a wad gun and because he knew I wouldn't shoot it enough to wear it out, a Hardball Gun on a 1918 vintage Model 1911. Though they don't get shot that much any more, they are still two of my proudest possessions.

He was a fine machinist and gunsmith as well as being a good teacher if you could get past his gruff exterior and were willing to actually listen to what he said to do. All these years later I still think of him often.

Froggie

This question gets asked a lot now that we're in the middle of the great primer shortage. I agree with those who say you have to shoot what you have as long as it works in your guns.

My chrono could not find enough difference in speeds between magnum small pistol primers and standard ones to worry about, so at least in my guns I consider them interchangeable.

I have a lot more small rifle primers than small pistol primers so I made up some test rounds and found that the CCI #400 and Federal #205 rifle primers both worked reliably in my M&P pistols but the CCI #41 rifle primers did not fire half the time in the pistols. They work fine in the AR though, which is what they were designed for.

When I go "outside the box" I always do some testing before making up too many rounds.

You don't indicate which way you're wanting to "interchange" them; pistol to rifle or rifle to pistol?

Different guns will handle the primer swap differently.

In the .223 I've loaded mainly CCI-400 (SRP) but tried some CCI-550 (SPMP), with the exactly same full powder charge & brand manufacturer's case, & saw no observable difference.

It's been reported that they're the same. Identical? Dunno.

The CCI-41 primers can be substituted for a small rifle magnum primers (CCI-450).

.

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Waiting for the break of day