Do CCI 400 primers flatten easily

[dhm]

In another thread, a poster noted that CCI 400 primers tend to flatten easier than some others. Rather than hijack that thread, I decided to start another thread on that topic. Have others experienced it as well?

The only small rifle primers I have left are CCI 400s, and I've been somewhat alarmed at how flat they are after firing only moderate loads. No other visible pressure signs were observed. I'd never heard that they flatten readily until I read the previously mentioned post. In the old days, I'd work up loads using different primers and compare, but those days are gone.

[bigedp51]

CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
http://www.sksboards.com/smf/index.php?topic=56422.0

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]

They are equivalent to Remington 6 1/2's. If all they are doing is flattening you're getting off easy, they could be piercing. See above.

[tomme boy]

CCI has changed the spm 450 primer and is not the same anymore. Been that way for a couple years. This article needs to be taken down. It is spreading unsafe and dangerous info.

[AndyLate]

They displayed flattening with relatively mild loads for me. I am a pretty conservative reloader, I never used them for maximum loads and these are my only reloads that show any pressure signs. CCI 41 primers look the same before and after firing loads that flattened CCI 400 primers.

On the flip side, people claim to have fired 10s of thousands of 223 from ARs without a problem. I fired at least a 1000 myself, but use the 41 in AR loads now.

I assume they are safe for 223 because they are small rifle primers and CCI has no warnings or notes against using them in the cartridge.

Andy

[bigedp51]

CCI has changed the spm 450 primer and is not the same anymore. Been that way for a couple years. This article needs to be taken down. It is spreading unsafe and dangerous info.

I do not see any incorrect information for the CCI 450 primers, the point of my link was the CCI 400 primer has a .020 thick cup and not recommended for the AR15. The CCI 400 primer was designed for lower pressure cartridges like the .22 Hornet, and .30 Carbine.

Below a CCI 400 primer fired in a AR15 rifle with a .020 thick cup when .025 primers are recommended. And as you can see the fired primer below still has well-rounded edges and was not loaded hot.

[gunnerblue]

I typically use federal 205's in AR15's but have loaded and shot ~1k of 5.56 pressure ammo using the CCI 400. I experienced neither flattened nor pierced primers.

[DG23]

I do not see any incorrect information for the CCI 450 primers, the point of my link was the CCI 400 primer has a .020 thick cup and not recommended for the AR15. The CCI 400 primer was designed for lower pressure cartridges like the .22 Hornet, and .30 Carbine.

Below a CCI 400 primer fired in a AR15 rifle with a .020 thick cup when .025 primers are recommended. And as you can see the fired primer below still has well-rounded edges and was not loaded hot.

Care to cite any reloading manual that states CCI 400 primers are NOT safe to use in an AR type rifle? (Cause none of my Speer manuals say any such thing...)



About your picture - A firing pin with the proper (within spec) protrusion length (as measured in your bolt) does not do that. Aside of that, You could have corrected the pin that did that in less time than it took you to post the picture of the so called 'problems' the primers were giving you. A .005 thinner cup did not do that...

I am about 1000% certain that if CCI primers were somehow unsafe to use in AR type rifles that are within spec CCI would have told us long ago and there would be a special warning on the boxes.

[AndyLate]

I typically use federal 205's in AR15's but have loaded and shot ~1k of 5.56 pressure ammo using the CCI 400. I experienced neither flattened nor pierced primers.

It is odd. I know that excessive headspace or light loads can cause flattening, but primers looked the same with multiple rifles and reasonable loads (24.5 gr TAC w/55 gr bullet). I did not have pierced primers. I am pretty sure I only loaded one brick (1000 rds) in .223/5.56.

Andy

[DG23]

It is odd. I know that excessive headspace or light loads can cause flattening, but primers looked the same with multiple rifles and reasonable loads ...
Andy

Which is why trying to judge pressure by reading primers (flatness) is akin to reading tea leaves.

There is much more to it...


I can confirm your statement about excessive headspace causing / contributing to flattening as well. Mouse fart loads in my 460 Rowland flatten the hell out of primers when using short brass where using the same exact primers but in the 'correct' length brass for that chamber they do not flatten. Even as those loads go well beyond +p level loadings the primers still do not look nearly as flattened as the mouse fart loads in short brass do so long as the brass length (headspace) is correct.