6BR problems

[Loki2]

I chambered an 8 twist barrel in 6BR and I am having problems with pierced and cratered primers--My first load was 30 grains of varget rem 7 1/2 primers and 108 Bergers every primer pierced--Next load was 29 gr Varget velocity 2700 shot 4 shots every primer pierced plus a stuck case I had to tap out with a cleaning rod I think the barrel is an 8 twist It was originally a 6 XC I cut the chamber off and went with the 6br--Any help will be appreciated

 

[mmcu]

If you're piercing Remington 7-1/2 primers and are having to tap out cases with a cleaning rod, you're running too hot of a load.

Start with a much lower charge and work your way up to a safe and accurate load.

 

[Loki2]

30 grains of Varget is what most people shoot. If I go to 28 grains the velocity will be in the 2600 range

 

[mmcu]

It really doesn't matter what most people shoot.

The important thing is what shoots safely in YOUR firearm.

 

[SteveOak]

Have you verified the neck dimensions?

 

[Dolomite]

what brass? Alpha? Chamber specs?

 

[Loki2]

Brass Lapua--Not sure on the chamber specs it is a no turn neck--I have used it on other barrels and never had a problem

 

[CJ6]

Have you actually measured your chamber length versus case length?

 

[mmcu]

Not sure on the chamber specs it is a no turn neck

In your original post, you stated that "I chambered an 8 twist barrel..." then go on to say "Not sure on the chamber specs...."

Did you actually chamber the barrel, or did someone else? What's the freebore and neck dimension?

If your barrel has a tight neck, or short freebore (having to seat the 108 Berger deep in the case), would both easily contribute to a "typical" load being too hot in your rifle.

 

[Loki2]

In your original post, you stated that "I chambered an 8 twist barrel..." then go on to say "Not sure on the chamber specs...."

Did you actually chamber the barrel, or did someone else? What's the freebore and neck dimension?

If your barrel has a tight neck, or short freebore (having to seat the 108 Berger deep in the case), would both easily contribute to a "typical" load being too hot in your rifle.

The neck is a no turn neck the freebore is for berger 105 bullets I don't have to seat the bullets deep in the case--I chambered the barrel myself with a reamer that I have done 3 other barrels with and had no problems

 

[Loki2]

30gr. is where some guys end up, but probably not a good place to start.
Are you sure you’re not using REM 6 1/2 by mistake.

I am using remington 7 1/2 primers not the 6 1/2

 

[AlNyhus]

How is the clearance between the pin tip and pin tip hole in the bolt face?

 

[Sniperhandle]

It's most likely the firing pin hole is too big. Have it bushed and the firing pin turned to match and your problems will be over. Is this a Remington?

 

[Loki2]

How is the clearance between the pin tip and pin tip hole in the bolt face?

there is no play the pin fits snug in the hole

 

[Loki2]

Yes Remington 700

 

[Loki2]

I had a 308 barrel on this action and I did not have any problems with primers or pressure

 

[Sniperhandle]

Yes Remington 700

That's the problem, Your FP hole is too large. If you keep shooting it you will get a failure, Firing pin springs sometimes get broken from the gases and there are most likely already primer blanks inside of your bolt which will cause misfires. 6 BR is a hot little round.

 

[Sniperhandle]

For some reason 30 calibers don't seem to be affected as bad, Once you get to 6.5 is when it starts to show problems, At least that has been my experience. Show a pic of your 308 primers and I will be willing to bet they are "Extruded" This is where the cup flows past the firing pin and into the space between and it and the hole, The extrusion will stick up proud.

Edit: Here is a pic I grabbed from Google, See how the cup material sticks up proud.

 

[Sniperhandle]

I can explain it like this, If you put a piece of glass over a 3 inch hole you can step on it and it won't break, You put it over a 6 inch hole and it will break. The same thing goes for the cup, The surface area of the firing pin hole is too large to hold the pressure, If you reduce it, It can hold it fine.

 

[Loki2]