Ok what is the difference between Small Pistol and Small Rifle primers? Let’s exclude the obvious such as pistol and rifle designations. The cups are identical outside diameter and the cup wall thickness is the same then is there a material difference? The anvil is different? Primer compound mixture assumption is that the rifle mixture is different with a hotter and longer duration ignition burn?

Did substituting small pistol with small rifle primers come into usage with the 38 Super and compensators?

Ok what is the difference between Small Pistol and Small Rifle primers? Let’s exclude the obvious such as pistol and rifle designations. The cups are identical outside diameter and the cup wall thickness is the same then is there a material difference? The anvil is different? Primer compound mixture assumption is that the rifle mixture is different with a hotter and longer duration ignition burn?

Did substituting small pistol with small rifle primers come into usage with the 38 Super and compensators?

Dennis,
I have an idea but, do you know the answers to your questions?

Dennis,

I don't know if the cup thickness is the same or not, which really doesn't say anything, since it could be a difference in the C260 alloy used to form the cup.

I do know the small rifle takes more hammer fall to ignite, which would lead me to believe there is a difference in at least the hardness of the cups.

I've used CCI 400s for over 30 years in .357 Mag and a lightened mainspring will not ignite them. When I replaced the mainspring in my M28-2 with a stock mainspring, the ignition problem with CCI 400s went away.

There is no hidden agenda on my part. Yes I have my thoughts on the subject. As Paul stated cup hardness which indicates differing cup material specification between small rifle and small pistol most likely is a factor. Primer compound mix contributing factor? I’m’ just asking questions.

No, I didn't think there was, just sometimes we ask rhetorical questions. Something to stir the old thought machine.

Here is a home-made tester page. I thought it was kind of ingenuous.
http://www.castingstuff.com/pr...esting_reference.htm

I have several calls into primer manufacturers and am awaiting their calls.

I did call one powder manufacturer and they stated that they don't have anything to do with primers other than make a solution for making primers. Of course they only sell that to the industry!
At any rate, they said that the only difference is their "brisance" and cup hardness. Of course size is a factor on the "large" side of things.

Cup hardness translates to the resistance of the primer to extrude under high pressure and the striking force required to ignite it.

When I have some verifiable information, i will post it.

Thanks for stirring this discussion.

My understanding Dennis has always been what Skip just posted? The explanation always given was that of primer body durability under pressure. Kudos' to Skip on following through with actually contacting the purveyors!

Federal returned the call first.
Here is what they had to say.

In order of "hotness", brisance, coldest to hottest it goes like this:
The order is the same for either large or small primers.
Standard Pistol Primers/Match Grade Primers
Magnum Pistol Primers
Standard Rifle Primers/Match Grade Primers
Magnum Rifle Primers
"50cal" Primers
The technician also stated that the other difference is cup thickness. Not so much hardness but thickness. The thicker primers are rifle ones and they are meant to withstand the higher pressures of most rifle cartridges.
He said there are problems going either way. Light strikes with rifle primers in handguns and pierced ones in rifles with handgun ones.

I will post other information as it becomes available.

Something to read:

http://www.jamescalhoon.com/primers_and_pressure.php

(As a note of interest, small pistol primers are .017" thick and large pistol primers are .020" thick.)

Another factor which determines the strength of a primer cup is the work hardened state of the brass used to make the primer cup. They are made with cartridge brass (70% copper, 30% zinc), which can vary from 46,000 psi, soft, to 76,000 psi tensile strength when fully hardened. Manufacturers specify to their brass suppliers the hardness of brass desired. I was not able to test primer hardness, but an educated guess says that a primer manufacturer would choose a harder brass in order to keep material thickness down and reduce costs.

I think I need to do some of that case head measuring thing with "THE LOAD". I wonder what I would find out!

I may find out that it is out of this world! I know I didn't feel the need to use a small rifle primer for it.

This could turn into an interesting experiment!

We are normally best served using the correct primers for the correct purpose (SP with pistols and SR with rifles) unless there is a COMPELLING reason to change.

As a for instance, it is RECOMMENDED to use small rifle primers in the .45 Casull (I think they would have been better to have stayed with Large Pistol primers but that is another story entirely). The pressure that the factory Casull's operate at require thick, hard cups to avoid cup flow at the firing pin indentation (which, at best, could tie up the revolver).

Small pistol primers have been recommended by some in the .22 Hornet. Accuracy may be better in that very small rifle case and normal pressures do not exceed small pistol specifications. Small pistol primers are used with the .357 Magnum and it can operate over 40,000 psi which is the same pressure level as the Hornet.

I try to use the correct primers for the job.

Regardless which primer you use you MUST work up the load again if you change primers in full loads - otherwise you could easily get into trouble.

FWIW
Dale53

You know Dale, I used to think that was just so much "hooey" that I never really took the time to do it. I would change components at random with no thought about the outcome. Let me state first of all though that 99.999999% of all of my loads are target type in nature. Most of them are smack dab in the middle of the data. Nothing barn burning to be sure. 200gr LSWC in 45ACP doing about 850fps hardly qualifies for "smokin' hot", that's for sure.

Then I loaded some different bullets with the same setup and powder and weight and ..... ended up with a load that was a good 30fps faster from the same gun. These loads were in the same velocity range only in the 40S&W, a cartridge well known for pressure issues.

Take a look at the thread I have about my 40S&W loads using SR4756. Something to consider to be sure!

smith crazy;
My awakening came about thirty years ago. I was deep into IPSC and had been shooting the Classic H&G #68 bullet at a power factor of 180 (which was required at the time). My load was probably about 950+. May have even been 980 fps. Due to circumstances, I ended up with a nice four cavity H&G #130 mould. Using the same load (well, heck, they were the same weight ) and after shooting a couple of thousand of them noticed the slide cracked on my 1911 .45 ACP. In three places... In my personal investigation that followed, I chronographed that load and it was doing 1100 fps . That is TOO much of a good thing. Then, knowing that no one thing puts you on a collision course (but two or three things coming together) I weighed my slide spring. It had sagged to 12 lbs! Standard 1911 is 16.0 lbs. So, the two things coming together did in my slide. My slide was a used military slide when I had my gun built of parts. Fortunately, my gunsmith had a nearly new Colt Series 70 slide that he sold to me for a very friendly price (I swapped him my old slide which went to Clark to make a long slide out of) and was back in business in a couple of days. I had some standing in the competition community and my 'smith was VERY understanding and accommodating - one of the REALLY good guys.

For those just starting, the H&G #130 is a superb target bullet and ran through my extensively reworked 1911 like a dose of salts. However, it had considerably more bullet down inside the case seriously reducing case capacity and raising pressures (and velocity) even tho' it weighed the same as the cast bullet it replaced. Oh, I got away with it for a time but the day of reckoning DID arrive.

So, the moral of the story (after I replaced my spring with a Wolf 18 lb spring and weighed it regularly thereafter) is if I change ANYTHING I recheck in every particular.

Dale53

For what it's worth, here's what Speer #7 said about CCI pimers.



With very little difference in energy, I have substituted small rifle primers in numerous .357 Mag loads, especially when I load 14.0 gr of SR 4756 and a 125 gr bullet.

The difference in energy seems small (I am looking at the difference between small pistol and small rifle magnums). However, the percentage difference is significant (about 24%). Understand that the primer is the initiator (starts the "big light"). I don't really want to change something arbitrarily in the range of 24%.

Best to work the load up when you change components. I remember standing next to a fellow on the trap line with a fine Pigeon Grade Model 12. When he fired, the gun locked up (the Model 12 Winchester is one of the strongest shotguns ever made). I looked at the shotgun, and the shell head had flowed around the breech bolt and spread the receiver. A VERY expensive lesson on blindly changing components. If that had been a fine double I would have been picking shrapnel out of my hair...

Just because a feller can get away with it doesn't make it right...

Dale53

Let me say that I found the article yesterday after posting the subject of small rifle and small pistol primers. While informative I do not readily accept the articles information totally. The information on primer cup measurements and material was informative. The triad of cup thickness, material specification, and priming mixture/brisance are the apparent differences between small pistol & small rifle primers.

As for the application of small rifle in place of small pistol primers that’s an individual’s decision. In certain shooting disciplines and applications the use of small rifle in place of small pistol primers as been practiced and written about. I’m not advocating using one in place of the other. On the other hand I’m not being dismissive of it either. It would be of value to know the resultant pressure differences between the two primer types.

Many moons ago I happened to be on vacation in the Lewiston ID area and The Bride and I stopped by the CCI plant that is located there. We the the "Fifty Cent Tour" as apposed to the 'Nickel Tour'. I was a FFL holder and working Deputy Sheriff at the time and that may have had something to do with it but I'm guessing it had more to do with the fact that The Bride knew what an primer "anvil" was when the Gentleman was first talking to us in his Office.

His name was Elmer Imathern(sp?) and he had just finished authoring/editing the latest edition of their Speer Reloading Manual. His statement to us was pretty much to the effect that switching this primer for that primer isn't a real good idea. He further stated that if you change from Standard to Magnum or from Pistol to Rifle you should back off your load by 10% or by 20% if you are already at the Maximum and work up from there. Since those days I have heeded his advise and I began to see pressure signs much faster when I made one of these changes. In other words I found that it was pretty much of a PITA and the loads I was able to obtain didn't prove to be worth all the effort.

I got a call back from one of the major primer manufacturer's technical guys today. For that I am grateful, but not for his attitude. It was repugnant at best, down right rude and obnoxious at worst. For those reasons I won't post the company he was from.

Suffice it to say, they have had the last of my business in the primer department!

It seems our litigious society prevents folks from being personable too.

OK, what was said was that he wasn't about to give any "paper" information to me because it would end up on the web with his name tied to it with a supposed approval of the process of substituting rifle for pistol primers and such like.

Basically, all of our assumptions are correct with only one exception, material hardness. Material is all the same, at least in his company, but the thickness changes according to prospective use. Brisance and expected pressure are the main reason for the differences, at least according to him.

FWIW

C'mon Skip, tell us who he works for. Maybe he was just having a bad day. Maybe, as has been said in another thread, he should just deal with people on the internet.

Anyway, tell us. We promise not to spread it around.

__________________
It's around here somewhere!

My local supplier was out of federal 100 small pistol primers last trip. I picked up a supply of small pistol magnum primers(federal 200) and intend to use them for target loads in a 38 special. Using 3.4 grs of HP-38 and a Remington HBWC bullet. I figured to check the velocity against a regular primer and reduce the powder charge to get comparible velocity if the magnum produced a significant increase in velocity. Anyone see a problem with this approach? Hopefully accuracy will not be affected.

Dennis,

The load I use is supposed to be in the 45,000 cup range. I can't tell much difference when I use a SP or a SR primer, but of course I don't have any pressure equipment to check with.

My thinking is, there's a little more safety margin against pierced/blown primers at that kind of pressure, when I use a small rifle primer.

Precisely why I was told to use SR primers in my "race gun" loads. At that point, it made sense to buy only SR primers, as it:

1. Prevented the accidental use of an SP primer where an SR should be;

2. Provided an additional degree of safety in my other handgun loads, particularly the .40; and

3. Simplified inventory.

I have been using SR primers in my .40 and 9x23 reloads for several years without any negative effects.

As always; your gun, your health, your call.

I see that a conclusive answer is not forthcoming.Yes there are those that have and do use one in place of the other. The reality is proceed at your own risk should one decide to use small rifle in place of small pistol primers.

Good advice for ANY reloading information, especially that pulled off of forums.

FWIW, back when I shot lots of IPSC, I always used Winchester small rifle primers in my .38 Super reloads. Major power factor was 175 then, and most of us ran at or above 180. I was shooting mostly 124 gr. jacketed bullets at about 1450 fps. Small pistol primers would always flow, and fairly often pierce at that pressure level, but the small rifle primers barely cratered. Small rifle primers are the ONLY way to go with factory-level 9x23 loads, which run at rifle pressures.