why small pistol magnum / small rifle primers?

[Spray_N_Prey]

ok i'm going down the dark path. I told myself I would never consider shooting open until I made A class in production, well I made A class in Limited first, then L10 and revolver and finally in Production, so I bought me a barely (3000 rounds) used open gun. Now I always here about people using magnum pistol or small rifle primers and am totally new to open so feed my knowledge.

Thanks guys,

Shawn G.

P.S. I will probably be posting a lot of newb questions on here but you guys (BE.COM) are the best and I truly look foward to being educated.

[TwoShot]

I use small rifle primers in 9 major because the primer cup is thicker and gives a larger margin of safety.

[G-ManBart]

For one, we're running pressures that are on the high side, and often over SAAMI limits. Consider that we're getting roughly .357 Mag ballistics out of 9x19 and Super/SC, and it makes sense to run a matching primer. The other thing is a lot of us are running large charges of very slow powder and in my somewhat limited comparison testing, I think the hotter SPM and SR primers give a more complete burn.

I'd also say that it's really about reliability, not necessarily safety. The small rifle or SPM primers have either a thicker cup, a harder cup, or some combination of the two. Because they're thicker/harder it takes more pressure to make them flow and/or smear. If they don't flow or smear they won't plug up the firing pin hole with shavings (also why many run extended firing pins) or have shavings wind up mixing with lube/carbon/soot and plugging up the extractor tunnel. R,

[hitman]

Pressure, thats why we use them in Major 9 and 175PF 38 Super.

With the reduction to 165 I know lots of 38 people that have gone to SP.

I run SPM in my Major 9.

[Aircooled6racer]

Hello: Just like you I am just starting out in Open. I have used small pistol, magnum pistol and rifle primers. On my major 9mm I find the powder has alot to do with the primer flattening. 3N37 being the worst and then Silhouette and finally HS-6. These are all in the 171PF range. All the primers have gone bang so that is not an issue just the flattening. The other factor I have seen to the flattening is the brass. I am using mixed range brass right now and will use my sorted brass when I get better. Thanks, Eric

[gunracer38]

I have used SRP,MPP, and SPP in my 38 Super since the beginning. All have worked well. But I do prefer SRP. They seem to show little effect from the major loads. All using 3N38 or 3N37.

[RiggerJJ]

Rifle primers are not necessary if you find the correct combination of primer, powder, and bullets. Without spending a lot of money on special test equipment, running pistol primers and not seeing signs of over-pressure you can be reasonable assured that you are not running over-pressure (at least not too much) and have a better safety margin compared to someone that is running rifle primers with pressure signs.

IMHO, the people that tell you that you HAVE to run rifle primers in open guns are wrong. If you find that you just have to use a certain type of powder (for whatever perceived reason) that does flow a pistol primer, you are just covering up the fact that you are running massive over-pressures with rifle primers.

Start with pistol primers, try several powder and bullet combinations, (working the powder charge up slowly toward major) and avoid the combos that show pressure. If you find something you "like" and just gotta use it and it showing a just a bit of over-pressure, use pistol magnum primers. (as Bart says, we are pushing 9mm and 38 to magnum balistics anyway)

OR

try something else, and you WILL find combos that will work with pistol primers.

to me, the safety margin, wear and tear on equipment, and being able to reuse brass more is worth it in the long run.

jj

eta; also another reason to avoid rifle primers is that they have a tendancy to "blow by" the primer, thereby flame cutting the breach around the firing pin, because they don't seal as well as pistol primers, because they are made for much higher pressures than even open pistols generate...

Edited January 15, 2010 by RiggerJJ

[Rolex]

RiggerJJ- from what I understand- thats why we USE SRP.

So there is NO blow by into the breach face, and they fit

tighter into the primer hole? At least that is what I have

understood for many years. Am I bad?

[XRe]

eta; also another reason to avoid rifle primers is that they have a tendancy to "blow by" the primer, thereby flame cutting the breach around the firing pin, because they don't seal as well as pistol primers, because they are made for much higher pressures than even open pistols generate...

I have never had this happen in an Open gun, even running light (135 PF) steel loads. In extremely low pressure cartridges this might be the case, but I've not experienced it with any normal (even low pressure) race gun loading for steel or USPSA/IPSC. I've shot a couple hundred thousands rounds of race gun ammo, at this point - using everything from 185PF HS-6 loads to 135PF N320 loads, and a lot of other things in between.

In any reasonable Open gun load, both Winchester and Federal SR primers will seal up just fine (can't speak for CCI, Wolf, or Remington).

I run an N105 load that is within SAAMI spec at 175PF (and still has another grain to go before I exceed the loads VV publishes in their manual). That load is specified with a small pistol primer. Small pistol primers flatten out pretty well with that load - not enough to look poured in, but enough to give concerns about potential flow/shaving in the firing pin tunnel. I don't need a small pistol primer to withstand any pressure outside the cartridge's design. I use one to avoid a potential jam inducing condition from primer shaving.

[shootingchef]

I use whatever I can find. it's not the pistol vs the rifle, or magnums. It is the manufacturer, my open gun does not like Mag tec, or Wolf, but loves CCI, Federal and Fiocchi.

[calishootr]

I used to run rifle primers to negate the nasty cases of primer flow i was constantly getting, then the advent of the XL firing pin and i decided to try that, and small pistol primers(which were cheaper in my area at the time) and voila!!!! it went away, and ive never looked back have XL pins in both my open and limited guns....

[gunracer38]

10-4 Rolex

[GrumpyOne]

I run an N105 load that is within SAAMI spec at 175PF (and still has another grain to go before I exceed the loads VV publishes in their manual). That load is specified with a small pistol primer. Small pistol primers flatten out pretty well with that load - not enough to look poured in, but enough to give concerns about potential flow/shaving in the firing pin tunnel. I don't need a small pistol primer to withstand any pressure outside the cartridge's design. I use one to avoid a potential jam inducing condition from primer shaving.

I'm using VV N105 as well in 38 Super (10.2 grains over a 115 MG JHP) with Winchester SP primers. The primers have no flattening or cratering, and in fact, look exactly like any factory manufactured round that has been fired. Being fired out of an STI TruBor.

Edited January 16, 2010 by GrumpyOne

[tunakilla]

try small pistol primers first, if you see flow get the XL FP. If the primer flow goes away then you can use whatever is available, rifle, pistol, or magnum

[RiggerJJ]

RiggerJJ- from what I understand- thats why we USE SRP.

So there is NO blow by into the breach face, and they fit

tighter into the primer hole? At least that is what I have

understood for many years. Am I bad?

Isn't it accepted that SRPs are harder (the cup) than SPPs? That means that they won't seal as well in the pocket unless the pressure is higher, up at rifle pressures. they are rifle primers...

I'm no expert by any means, but the open guns I have examined that shoot SRPs have much more breach face cutting than the ones using SPPs...

jj

[Rolex]

Yes from what I understand the-SRP-are harder.

I have been shooting the same open gun for almost three years,

using SRP and True Blue. At this time I have not observed any

breach face problems. BUT I will start looking at the open shoot-

ers guns that I shoot with and see if I notice anything on their

guns. I have a great supply of WSP that I would like to use up!

[XRe]

Isn't it accepted that SRPs are harder (the cup) than SPPs? That means that they won't seal as well in the pocket unless the pressure is higher, up at rifle pressures. they are rifle primers...

It's not just accepted - the primer manufacturers will tell you so Dimensionally speaking, SP, SPM, SR, and SRM are all the same. They (should) all fit in the same primer pockets. LP(M) and LR(M) are dimensionally different - the rifle primers are taller, necessitating a deeper primer pocket in the rifle case.

From there, it depends on the manufacturer - in some cases, the difference between SP and SPM are just the dose of priming compound (the magnum primer having more to light the larger magnum powder charge reliably). In others, the magnum primer might be a bit harder, as well. The degree of difference in cup hardness between a manufacturer's pistol and rifle primers also differs between manufacturer, as do any differences in priming compound. And, you're correct - the harder the primer, the higher the initial pressure will have to be in order to seal the primer. However, depending on the manufacturer, the rifle primer can still be soft enough to seal up just fine on normal mid-range pressure pistol loads. This is the case with Fed and Win SR primers.

I'm no expert by any means, but the open guns I have examined that shoot SRPs have much more breach face cutting than the ones using SPPs...

Realize that high pressure loads can result in a beating on the breechface that leaves an indentation of the casehead (including a "ring" around the primer area) that can resemble breechface cutting - but isn't. In examining quite a number of open guns, breechface wear due to high pressure loads is far far far more common than any kind of breechface pitting due to primer blow by... The blow by pitting can be detrimental to reliability (it makes a rough surface on the breechface that eventually is not correctable), but the beating is eventually fatal to the slide (slide cracks, etc...)

[RiggerJJ]

Yes from what I understand the-SRP-are harder.

I have been shooting the same open gun for almost three years,

using SRP and True Blue. At this time I have not observed any

breach face problems. BUT I will start looking at the open shoot-

ers guns that I shoot with and see if I notice anything on their

guns. I have a great supply of WSP that I would like to use up!

Feel free to send em all my way, I love WSPs!

Isn't it accepted that SRPs are harder (the cup) than SPPs? That means that they won't seal as well in the pocket unless the pressure is higher, up at rifle pressures. they are rifle primers...

It's not just accepted - the primer manufacturers will tell you so Dimensionally speaking, SP, SPM, SR, and SRM are all the same. They (should) all fit in the same primer pockets. LP(M) and LR(M) are dimensionally different - the rifle primers are taller, necessitating a deeper primer pocket in the rifle case.

From there, it depends on the manufacturer - in some cases, the difference between SP and SPM are just the dose of priming compound (the magnum primer having more to light the larger magnum powder charge reliably). In others, the magnum primer might be a bit harder, as well. The degree of difference in cup hardness between a manufacturer's pistol and rifle primers also differs between manufacturer, as do any differences in priming compound. And, you're correct - the harder the primer, the higher the initial pressure will have to be in order to seal the primer. However, depending on the manufacturer, the rifle primer can still be soft enough to seal up just fine on normal mid-range pressure pistol loads. This is the case with Fed and Win SR primers.

I'm no expert by any means, but the open guns I have examined that shoot SRPs have much more breach face cutting than the ones using SPPs...

Realize that high pressure loads can result in a beating on the breechface that leaves an indentation of the casehead (including a "ring" around the primer area) that can resemble breechface cutting - but isn't. In examining quite a number of open guns, breechface wear due to high pressure loads is far far far more common than any kind of breechface pitting due to primer blow by... The blow by pitting can be detrimental to reliability (it makes a rough surface on the breechface that eventually is not correctable), but the beating is eventually fatal to the slide (slide cracks, etc...)

Yea, I've seen the difference...

jj

[Rolex]

Stop by the house- I might just give you some!

[THM7]

Well I would avoid Fiocchi SRP....after noicing some erosion I examined some of my brass and there was a slight black ring around the primer pocket (blow by?). Anyway I went back to WIN SPP and have had no more problems.....it might be a Fiocchi primer issue.