primer piercing ?

[Link]

The load that seems to be accurate for me in my 6ppc is 27.1gr. h4198 14 Twist and 68 gr Barts. However it seems to be crater ing my CCI 400s and actually punctured [blew a hole ] in a primer the other day. The primers don't seem to be flowing around the edges and my bolt lifts nice and smooth. I tried wolf smr and they seem to work better, but I don't think I'm getting the accuracy with them as the CCIs. Should I try a lil more powder with the wolf or am I at the max? Or should I back off even with the wolf?

Ideas ?

thanks Link

 

[Hombre0321]

I have had a few rifles that pierced primers, usually Factory Rifles I might add. The first time it happened I went the load route down in powder, changed primers etc. What I found is it wasn't the load at all, in every case I have had it was the firing pin hole being to large. It is a simple fix ship the bolt off to GreTan let him bush the firing pin hole and you are done. Turn around time was less than a week for me as well.

You might look there first and save yourself a ton of fixing stuff that isn't the problem. never can tell...

RS

 

[CatShooter]

The load that seems to be accurate for me in my 6ppc is 27.1gr. h4198 14 Twist and 68 gr Barts. However it seems to be crater ing my CCI 400s and actually punctured [blew a hole ] in a primer the other day. The primers don't seem to be flowing around the edges and my bolt lifts nice and smooth. I tried wolf smr and they seem to work better, but I don't think I'm getting the accuracy with them as the CCIs. Should I try a lil more powder with the wolf or am I at the max? Or should I back off even with the wolf?

Ideas ?

thanks Link

If the primers are not flowing around the edges, then you don't need the bolt to be bushed.

The 400 primer has a much thinner cup, and it will blow at safe and sane pressures. Try the 450 or the BR-4 primers. they have a 25% thicker cup (and it is harder).

 

[brxbrad]

Wrong primer......Use Tula SRM or CCI 450's or any thick cup primer for small rifle.....

 

[bigedp51]

Bumping the shoulder back too far can cause a pierced primer, the firing pin will act like a cookie cutter when the primer flows back over the firing pin.

The AR15 is noted for this problem with the thinner cup primers and and it is recommended that the thicker .025 primer be used to prevent this.

The firing pin hits the primer driving the case forward, the cartridge goes bang and the chamber pressure forces the primer back over the firing pin and punches the firing pin dent out of the primer. This is a common occurrence in milsurp rifles when the resizing dies are not properly adjusted. It can also happen if the primer pockets were uniformed too deeply allowing excessive back and forth movement of the primer.

On a rifle the head clearance or "air space" between the rear of the case and the bolt face is normally the problem which causes the firing pin to act like a cookie cutter and punch the center of the primer out.

 

[WyoWindage]

Ahha, I bought 2K CCI400sr primers, thought I hit a gold mine. They started piercing with Varget in 6br, when Rem, Fed, WW didn't. Think I know why now. Thanks. Ron.

 

[Link]

Thanks again Gentlemen.

Love the illustration.

I'm off to the reloading bench to load using some BR4s and some 205Ms

It might be a few days before we get a chance to test for accuracy.

Link

 

[bigedp51]

I'm not sure which label fits...............

1. The little Dutch anvil who tried to stop the leak.
or
2. The ruptured naval primer.

There isn't any doubt what pressure can do a anvil.

Photos from AR15.com