Interesting behavior, at least to me

[the45er]

With the critical shortage of small pistol primers going on, I tried something yesterday that yielded "interesting" results. I found 500 old CCI small rifle primers in my inventory. Having read in several forums where people have successfully used CCI 400 small rifle primers as substitutes in small pistols by backing charge way off, I decided to try it in a 40 S&W.

I loaded 10 rounds using 2.8 grains of Bullseye over a 180 grain HiTek-coated lead bullet. I loaded them in a mag for one of my striker fired pistol. Three of the ten failed to fire, even with an apparently good strike on the primer. OK, I concluded that these were too old to used reliably even though the ones that did fire seemed very mild in recoil yet still cycled the pistol. There were certainly no signs of over-pressure.

I was going to toss the three failed rounds but decided just for the heck of it to see if they'd fire in a hammer fired pistol. I didn't expect them to, but they did! What's up with that?

Lastly, and perhaps of more concern and reason not to use them in pistol loads was that I noticed when shooting them in both guns, I could see sparks fly up from the ejection port on both guns. I then fired my normal reloads in both guns and there were no sparks. Obvious conclusion - NOT GOOD, so no more magnum rifle primers in pistols. However, I wonder what causes this? Seems like over pressure would cause more recoil and deformed brass, neither of which were in evidence. Any ideas?

[Unclenick]

The firing in your revolver suggests the primers were not fully seated initially and needed the first blow to finish that job and sensitize the primer by compressing the mix between the cup bottom and anvil a bit. This happened with pre-1992 CCI primers a lot because the cups were significantly harder to seat than some other brands, making short-seating easy to do by mistake. In '92 (IIRC) the CCI primer lines were revised to eliminate the cup lip metal smearing that caused this. But the primers could also just be old and needed that compression. Try seating them really hard.

Sparks from the ejection port usually indicate low-pressure firing that failed to expand the case enough to seal the chamber gases in the chamber, so some gas and powder particles (some burning) got out around the case. You should see soot on the sides of the cases and perhaps powder particles in the chamber when this happens.

Given that you had a failure to fire and a low-pressure sign would seem to indicate the primers were weak. However, it may just be the seating problem, as primers that go off marginally do not produce as strong an ignition flame and produce wider velocity variation than those which are ignited smartly.

[74A95]

Some striker fired pistols have problems setting off rifle primers. They just don't hit the firing pin as hard as a hammer fired pistol.

Many people use rifle primers in their pistols. People shooting Major power factor ammo in IPSC/USPSA in their 9mm / 38 Super pistols often use rifle primers. I use (countless thousands of) Federal small rifle primers for many of my loads in those calibers. They work fine. Have also used some CCI small rifle primers. There have been some ignition issues when using light hammer springs that many competitors put in their 1911-type race guns, but they worked fine for me with a 19-lb hammer spring.

I don't know off the top of my head if I've tried many magnum rifle primers for these loads.

I get sparks from my ejection port with some powders with pistol primers, so there is no obvious concern that only rifle primers do that.

[74A95]

Originally Posted by Unclenick

The firing in your revolver . . .

He didn't say revolver. He said hammer fired pistol.

[Aguila Blanca]

Rifle primers are harder than pistol primers. That alone could explain the initial failures to fire.

What's your usual load for that bullet with that powder? You wrote that you have read you can use small rifle primers in pistol loads if you back the charge "way" off. That's not what I have read. I have read that you might want to decrease the charge slightly. I suspect that your spark problem is that you backed the charge off too much.

[ghbucky]

My understanding was that you can use small rifle (not sure about magnum rifle, which the OP mentions) but you need to start load development from scratch for using small rifle primer.

[the45er]

4.3 grains of Bullseye over a 180 grain Hytek-coated lead bullet from summersenterprisesllc.com

I was worried that the small pistol magnum primers might be real hot, so I backed the load way down. From the other posts, I can see that the sparks I saw were probably not due to over pressure, especially since there were no other signs of excessive pressures.

The hammer fired pistol that did fire the ones the striker fired pistol didn't was not a revolver, it was a Springfield Armory EMP 40 S&W.

From what I'm gathering from the responses so far, I could probably safely bump the load a few tenths of a grain and achieve a load that would not "spark" in the EMP?

[reddog81]

Rifle primers are harder so its no surprise some didn't fire until the hammer fired gun was used.

The job of the primer is to ignite the gun powder. In order to do this when the primer lights off it sends a mixture of lead styphnate out through the powder column. It shouldn't be too surprising that rifle primers send more noticeable sparks out the barrel as more lead styphnate is used in rifle vs small primers. The powder charges in small rifle cases can be 10X the amount of powder used in small pistol cases so something has to be different.

[Unclenick]

Rifle primers are not universally harder than pistol primers. You have to look at the specific case. You can get an idea by measuring the thickness of the cups of decapped primers, though cup thickness need not be the only determining factor.

With any luck, a primer won't send lead styphnate out through the powder, but rather its combustion products as gas and flame and sparks.


The45r,

Roger on the pistol vs. revolver. What I get for posting before my second cup of coffee has brewed. The effect should be pretty similar, though. Everything hinges, for comparison, on how much impact energy the firing pin has, versus what the striker spring could develop. Did you make a second try in the striker gun? If that failed to fire them, its an impact energy difference. If it fires them, its most likely the hard seating issue.

[the45er]

that rifle primers send more noticeable sparks out the barrel

The sparks were visible coming up from the ejection port in the slide, not out the end of the barrel. That's what I didn't understand.

[reddog81]

Originally Posted by Unclenick

Rifle primers are not universally harder than pistol primers. You have to look at the specific case. You can get an idea by measuring the thickness of the cups of decapped primers, though cup thickness need not be the only determining factor.

I've heard that CCI small pistol magnum primers are the same as small rifle. However both of those are probably slightly thicker than regular small pistol primers typically used in 40 S&W.


Edited to reflect I went back and reread original post...

[Aguila Blanca]

Originally Posted by the45er

My usual load for the 40 S&W is.................
4.3 grains of Bullseye over a 180 grain Hytek-coated lead bullet from summersenterprisesllc.com

Is 4.3 grains at or near the maximum for that powder and bullet combination?

My understanding is that in general starting loads are 10% to maybe 15% less than maximum loads. If we assume that your usual load of 4.3 grains is somewhere near maximum, 10% less would be 3.9 (okay, 3.87) grains. 15% less would be 3.7 (3.655) grains. You went all the way down to 2.8 grains. That's a reduction of 35 percent.

I don't think small rifle primers are so much hotter than small pistol primers that you need to reduce your normal load by more than one-third. Try 3.5 grains and see what happens. My guess is that you can go even higher than that safely.

[reddog81]

Originally Posted by the45er

that rifle primers send more noticeable sparks out the barrel

The sparks were visible coming up from the ejection port in the slide, not out the end of the barrel. That's what I didn't understand.

With that light load the brass case probably didn't seal the chamber like normal.

[the45er]

Is 4.3 grains at or near the maximum for that powder and bullet combination?

summersenterprisesllc.com does not publish data for their bullets. The bullets are 180 grain lead bullets with a purple "Hytek" coating (not copper) on them. The lowest recommended powder drop Alliant publishes on the internet for 180 grain bullets and Bullseye powder is 5.7 grains, but admittedly, these are for jacketed bullets.

[Unclenick]

Originally Posted by reddog

I've heard that CCI small pistol magnum primers are the same as small rifle.

They used to be, but I spoke with CCI this morning and they say that has changed and that they both now have different quantities of different priming formulations and that the primer cups for their #400 small rifle primers are now thicker than on the small pistol magnum primers.

[Aguila Blanca]

Originally Posted by the45er

The lowest recommended powder drop Alliant publishes on the internet for 180 grain bullets and Bullseye powder is 5.7 grains, but admittedly, these are for jacketed bullets.

So you are at less than half the starting load for a jacketed bullet?

It's a minor miracle the bullet made it out of the barrel. [/sarcasm mode]. IMHO, you not only can safely increase the charge, you should increase the charge.

[the45er]

............I'm talking 4.3 grains now. The 2.8 grains with the magnum rifle powder shot ok, just a lot of "sparks" out the ejection port. I'm thinking the explanation that the casings didn't expand to seal the chamber might be right.

[Aguila Blanca]

Originally Posted by the45er

Originally yes, but....................
............I'm talking 4.3 grains now. The 2.8 grains with the magnum rifle powder shot ok, just a lot of "sparks" out the ejection port.

Where are you talking 4.3 grains? You said that's your normal load for that bullet and powder, but that you backed way off from that when you loaded with the rifle primers. I don't see anything in this thread about using 4.3 grains with the rifle primers.

I'm thinking the explanation that the casings didn't expand to seal the chamber might be right.

I think that's what everyone has been trying to tell you.