Home Forums Hunting & Shooting Ask The Gunwriters Blowing Primers - Pressure Levels

Winchester primers are typically softer, and flow, resulting in the piercing mentioned by Denton above.

You will never pierce a CCI primer, they will always blow.

Federal primers will actually flow back into the firing pin hole in the bolt face giving a very distinct artifact on the primer.

In general, all else being equal, typically Winchester primers will pierce before CCI's will blow.

[/quote]

Winchester primers are typically softer, and flow, resulting in the piercing mentioned by Denton above.

You will never pierce a CCI primer, they will always blow.

Federal primers will actually flow back into the firing pin hole in the bolt face giving a very distinct artifact on the primer.

In general, all else being equal, typically Winchester primers will pierce before CCI's will blow.
[/quote]

That's been my experience as well.

One of the interesting things I've learned in talking industry people is the CCI 41 small rifle primer--the one designed for AR-15 and other semiauto .223/5.56 loading--doesn't actually have a tougher cup, as many would assume. Instead the "geometry" of the cup and anvil is changed from the standard CCI 400 SR primer is changed.

Yep, MD ‘s dead nuts on what I experienced over time.

I used to use winchester primers religiously...they are the only one’s I’ve had pierce.
them moved to remy benchrest, tried some federal and was suprised at it...

Finally made the jump to CCI and provided they are available I’m happy.

You may have witnessed the pressure excursion that the 243 is infamous for, especially if the throat was worn. My theory is it is due to the powders used, at that time some type of bulk powder similar to 7828 and to throat wear and variations. The same thought on the 7RM which had the pressure reduced after it exhibited greater than acceptable pressure excursions. I have loaded many hundred of these two rounds and not witnessed this phenomena. The 243 was plenty worn and the 7 RM I shot the barrel out at around 3,000-3,500 rounds. It was probably gone before but this was at the point it started to shoot erratically and larger groups across the board.

I believe what Charlie Sisk was saying is that a tighter chamber doesn't show pressure signs or blow primers as soon as a looser chamber would. Is the Ruger Number 1 considered to handle pressure well and not show indications as much? I was getting flat primers with a #1 thought it was pressure but turned out to be tight primer pockets on new Nosler brass, the primers were getting the final seating when chambered. When shot they backed out some and were flatter than they should be. But an unfired round looked flatter too after clambering.

I've pierced a CCI primer, and blown a primer...

They do handle pressure well. My pressure sign is when the extractor fails to extract (slips over the rim) and I have to pry the case out with a screw driver.

You can also often knock a stuck case out of a No. 1 Or other falling-block SS) with a stout cleaning rod of the right diameter.

Leaked primer on my 700. Greg Tannel did the repair. This was not from high pressure. I was getting cratering at min loads due to the over sized firing pin hole. I lived with it until I took a leak. .257 Bee, Bartlein barrel Federal GM215M primers. First time that has happened. Zero pressure signs.

Had a couple of Winchester LR do the same as the above in a mildly loaded 257 Roberts.

15 or so years ago I got a deal on 1000 Rem 9 1/2 primers. I loaded a bunch of '06, 243 and 22-250 ammo and went shooting. I got several (many) pierced primers as pictured in the above post. All 3 rifles were affected. I wrote Remington and they wanted primers of the lot I used, fired cases and unfired cartridges. I sent them out and got the reply that since they had no control over the storage or use of said primers, I was SOL. So no answer and no more of my money spent on Remington components. All rifles have pitted bolt faces but otherwise perform well.

I had a CCI primer blow in the 9.3x62 using 66gr of big game in a Lapua case with a 286gr Partition. I subsequently performed a node test and discovered that I basically stopped gaining any velocity beyond 64.8 grains, so that's what I use now and have not had any more problems.

This is the same results I've had, I had a load I shot for years that was fast, but you could load the cases 7-8 times, nothing looked out of the ordinary, when I got a pressure trace, they averaged 68k psi with some up to 71k. I backed it off after that. I think it takes 80k psi to blow a primer as a rule, and my one blown primer was just like MD, 4th or 5th shot when it was hot and I left it in the barrel for a while before I shot it and let it heat soak really good.

Just for fun I went looking for bond strengths.
An average Ni-Ni bond was reported at 81.75 (didn't see the units)

Tin-Brass alloys are somewhat more difficult to find...
I wonder if the nickel plating on CCIs results in a more catastrophic failure as a result of a slightly higher bond strength than the underlying brass.

Just supposing...

Edit:
More digging and Capitalcartridge.com posts a factoid that nickel coated brass is more fragile or brittle.

That would suggest a more dramatic failure mode...

For what it's worth.