Random holes in primers

[McLarenross]

I was doing load workup for a friends AR-15 and every now and then we would get a pierced primer. It was random and didnt happen at the higher loads, just the lower charges. We were loading 23.8gr to 24.5gr of RL-15 under a 77SMK with CCI 400s in WCC cases. Velocities were from 2650 at the lower charges to 2740 on the high end. Its a 20" AR varmint gun. There were no other signs of pressure at all. Primers were nice and round and there were no extractor marks. Any ideas whats going on?

 

[Hummer]

Re: Random holes in primers

Is the CCI400 the Milspec Primer? If not you need the milspec primers from them.

 

[Agent Ronin]

Re: Random holes in primers

CCI#44 is the milspec small rifle primer.

 

[ChadTRG42]

Re: Random holes in primers

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Agent Ronin</div><div class="ubbcode-body">CCI#44 is the milspec small rifle primer. </div></div>
Actually, I think it's the CCI #41 for the mil spec primer.
This should solve your problem.

 

[McLarenross]

Re: Random holes in primers

These are standard CCI small rifle primers, I think thats CCI 400. Ive shot hundreds upon hundreds of these primers through my, and a number of other AR-15s and never had this problem. Why would this one do it? Is it hurting anything to run it this way?

 

[former naval person]

Re: Random holes in primers

Pierced primers can erode and pit the bolt face.

 

[Grump]

Re: Random holes in primers

Inspect the firing pin.

Inspect the loads for crud getting pressed on in the primer seat operation...that can be a problem with progressive presses cycling crud around the shellplate merry-go-round.

 

[GreatGonzo]

Re: Random holes in primers

Odds are that you will need to replace that firing pin if it has happened more than a few times. A bad firing pin could cause this, and this one is probably eroded due to pierced primers.

 

[McLarenross]

Re: Random holes in primers

This gun has had less than 200 rounds through it. All was factory ammo.

 

[Short Round]

Re: Random holes in primers

BTDT, just a handful of pierced primers will burn the tip of a firing pin. After that the F'd up firing pin will pierce the primers on it's own. Sometimes you can dress the tip of the firing pin but's much easier to replace it.

Also had issues with the CCI 400 and the new WSR's with medium to medium high charges.

 

[tomme boy]

Re: Random holes in primers

I have not had a problem until lately. I just ran out of my primers I have had for a long time. When I started to use the primers in the new style of box (all blue), that is when I started to have random primers that had pierced. Wasn't it the same time they switched colors that primers and powder started to get scarce? I wouldn't put it past CCI to have went to a slightly thinner cup to reduce cost and max profit.

 

[ChrisGarrett]

Re: Random holes in primers

I had some AR loads using some heavy bullets and had a few primers pierce. Looking at the tip of my firing pin under a 10x jeweler's loop, it's erroded off to one side of the crown, not quite at the tip.

Firing pins are cheap and I plan to buy a couple of spares at the gun show this week.

It happens, although mine hasn't pierced any other primers (400 rds) using RP green box and stuff I've loaded up, since then, the primer indents do show a roughness caused by the erroded shape, at the bottom of the radius.

Chris

 

[McLarenross]

Re: Random holes in primers

Interesting. I will pull the pin and see what it looks like.