UGH, another help with primers question

[taliv]

There’s a member on THR named slamfire who is passionate about this topic. He has compiled a list of reports of slam fires which are primarily in garands and AR15s in high power competitions. A large percent of the incidents mention cci400.
The link below has some of his commentary about the debate over the past 6 decades along with his list which is not a particularly quick read.

https://www.thehighroad.org/index.ph...#post-11153988

[TomMcC]

It makes sense that it really only happens in high power rifle when single loading. Were any of these rifles designed to be single loaded. Not really. As long as you're not doing this you'll never have a problem.

[Lefty223]

FWIW I do use CCI #34 NATO Spec Primers in my National Match Garand (< 1 MOA accuracy) but have never seen nor have had any issues w/ 5.56mm reloads using standard primer for the AR platform, as many others opined.

[bigedp51]

If you want to learn about the initial slam fire and other development problems on the M16 rifle the book below id full of information.

And again it is recommended to use primers with a cup thickness of .025 in thickness. And when Remington ran Lake City they used Remington 7 1/2 primers with a cup thickness of .025

Small pistol primers have a cup thickness from .017 to .020 and designed for lower pressures. And if you read the information I posted before the CCI 400 is the same primer as the CCI 550 Small Pistol Magnum.

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.

[TomMcC]

Did a bit of research and it looks like CCI doesn't recommend the 400 for the AR because of what has been stated. It's been years since I loaded them and didnt have any probs then, but...Seems like they may may be close to the Rem 6 1/2's. Those are definitely a problem at .223 pressures.

[czgunner]

Did a bit of research and it looks like CCI doesn't recommend the 400 for the AR because of what has been stated. It's been years since I loaded them and didnt have any probs then, but...Seems like they may may be close to the Rem 6 1/2's. Those are definitely a problem at .223 pressures.

I don’t doubt cci’s recommendation, but I haven’t ever had an issue using them in my AR15 hand loads.

[taliv]

Recommendations aside I have personally loaded over 50k 223 with cci400. I bought a lot before I knew. I suspect lack of cleaning has retarded the bolt velocity just enough to save me from slam fires.

Still I am cautious and never chamber a round in the house etc.

[TomMcC]

The 400 cup is .020" but maybe it's just made out of harder material. CCI has been know to have the hardest primers amongst competitive pistol shooters for years.

[AndyLate]

I have loaded and fired a bit (a few thousand?) of 5.56/.223 for use an ARs using CCI 400 primers. I have not had an issue with slam fires or ruptured/punctured primers, but the primers showed signs of maximum pressures with multiple mild loads. The mil-spec primers looked perfectly normal using the same loads in the same gun at the same temperatures.

Andy

[markm]

Same here with the 400s. I'll pick them up a thousand at a time for blaster ammo that I don't want to use my WOLF primers.

The only slam fire in .223 I've ever witnessed was with a ban era Korean AR style rifle. I forget what they call it. But it did slam fire once.