New to the 6mmBR and have questions

[montana_native]

I found a fantastic load for this thing with the 105 Amax. It is shooting under 1/4 MOA to 300 yards (as far as I've had it so far) with GM205Ms and 30.3 gr of Varget. It's a 25" 7.5 twist Bartlein barrel. Velocity is 2820 with single digit ES.


The problem is that approximately 1 of every 10 rounds gets a pierced primer. Years ago when I was pushing a 223 AI hard, I had to swtich to magnum primers (CCI450s).

Are magnum primers a must for a 6mmBR? I didn't think this load was too hot from all of the load data I have reviewed.

Thanks.

 

[smoking-brass]

Check your seating depth first....If it's in the lands to tight you are getting high pressures for that primer...i use cci 450's with hot loads in my br. And I have no primer problems.

 

[cocopuff]

Everyone told me to use mag. primers..I get a lot better groups with the small standard primers..Yes I have to agree,it sounds like you may be into the lands too tight. I had the same thing happen with a 22-250 once...Good luck with it..

 

[montana_native]

I'm about 0.010" into the lands. I guess I will back it out and see what happens. Thanks.

 

[Hal]

Have you used this rifle with other loads or can you trace the trouble to your current loads?

Things you might check, firing pin nose, try a different lot of primers or a different make of primmer with thicker cups.



Hal

 

[RDavies]

Are you getting loose primer pockets or sticky extraction?
I,m running an almost identical load in my 6BR (using russian primers) and was getting pierced primers with no other pressure signs. I later looked at the firing pin tip and found a chunk broken off the tip, making it look more like a chisel than a round tip.

 

[brxbrad]

Wolf SRM..Tula SRM...CCI 450 or BR2 primers.....Piercing will disappear

 

[montana_native]

Are you getting loose primer pockets or sticky extraction?
I,m running an almost identical load in my 6BR (using russian primers) and was getting pierced primers with no other pressure signs. I later looked at the firing pin tip and found a chunk broken off the tip, making it look more like a chisel than a round tip.

I am gettting no other pressure signs. Primer pockets are still very tight. I have some CCI400s and some CCI450s I will try.

 

[Travelor]

I have a 6mmBR that was built by Speedy Gonzales. It is a tight neck gun requiring turned necks, it will not shoot 30 grains of VARGET behind a 105 or 107 grain bullet without showing definite pressure signs. I switched to VV550 at 30.5 grains of powder and same bullet and primer. Groups around 2" at 600 yards and NO pressure signs and appropriate velocities. All loads with Lapua cases, Tula SRM primers, and 105 gr Berger Hybrids.

Might try this.

 

[roadkill61]

Just my thought but is it possible, since you are seated into the lands,that some rounds are a bit longer and are therefore "into" the lands just that much extra enough to cause that extra pressure.

 

[montana_native]

The CCI450s solved the problem and the accuracy remained the same. Thanks to all who responded with advice.

 

[jnyfeler]

The 6BR is notorious for piercing primers. You just need your firing pin turned and your firing pin hole bushed. Gre-Tan Rifles will do this with a quick turnaround allowing you to shoot whatever primer you want (CCI BR4 is my fave).

http://www.gretanrifles.com/services/viewEntry.jsf

Jeff

 

[MarkS]

+1 for what Jeff said. The 6BR will crater or punch a primer before you see pressure, due to the firing pin. if the 450's work, you will be ok. I have not had good luck with 450's in my 6br and 6BRX, they like 205nor BR-4.

Mark Schronce

 

[GaryCrow]

The CCI-450's and BR-4's have thicker metal in the cup than the Federal 205's or the CCI-400's. That's why they're recommended for the higher pressure loads.