Q. 6mmBR bore diameter?

[308BAR]

Ok, I'm doing a little research on barrels the 6mmBR caliber and I come across on the Shilen barrel site. They apparently have different bore diameters for the same caliber? Wondering what the you boys and gals are using as a bore diameter? I've check the 6mmBR site and I don't think I came across any info about this.

Is there any advantages to one over the other or are they all the same. Please school me, preferences, any information or help will be appreciated?

Or am I reading everthing wrong here?

w w w.shilen.com/chambers.html
from website:
6mm Norma BR (.272)
6mm BR (.263")
6mm BR (.270")
6mm BR (.266")
6mm BR Rem.

 

[Eagleye]

Those look like "throat" [neck] diameters, not "bore" diameters to me. The nominal "bore" diameter for the 6mm is .236-.237" and the groove diameter is .243" Regards, Eagleye.

 

[ben hunchak]

Some of those dia may require neck turning cases to make it all fit after the bullet is seated.

 

[308BAR]

Doh!!! Thanks guys.....theres just a lot of info to absorb. Is there any neck dia. preferences for shooters out there of this caliber?

 

[chajam]

.272 is the standard for a no turn neck, I have a shilen prefit for a savage with this neck diameter and it shoots great.

 

[guntech]

I suggest you use Lapua brass and a .272 no neck turn chamber.

 

[JasonYuke]

I agree 100% the ease of .272 will save you time like no tomorrow. I had a 262, and even though I only had 25-30 cases it was not much fun to replace them.

Most BR shooter go a bit smaller than .272 to get the snuggest fit in the chamber and throat.

Can also look at Sako USA PPC, the brass is a bit thinner, .270 if I recall

 

[308BAR]

.272 is the standard for a no turn neck, I have a shilen prefit for a savage with this neck diameter and it shoots great.

What finished length is your prefit barrel?

or

What would be the optimal for the 6mmBR?

 

[Mystic Precision]

As was said, those are the neck diameters of the chamber. If you want to neck turn, you prep your brass, seat a bullet and measure your outside diameter. Allow for 3 to 4 thou total clearance (1.5 to 2 thou per side) and that is the chamber size you want.

I do prefer to neck turn all my brass even if it just cleans up 70% of the circumferance.

Many shoot Lapua brass without turning. A bunch of shooters still turn Lapua brass. That is a personal thing and what you feel is necessary to drive them into one hole.

The 6BR is one of the most accomodating cartridges and work well from 20" to 30". Most competition F class shooters lean towards a longer pipe to max velocity. Most will have all they need with a 26" pipe.

Jerry

chajam, glad you are enjoying your Shilen.

 

[Ice-Pick]

Mine's a .268 neck , no turning for the BR
the 6 PPC is a .262 neck that has to be turned and made out of 220 russian cases.
I have em both. And I did get cartridge diagrams WITH meassurements from 6br .com

M.

 

[JasonYuke]

I agree 100% the ease of .272 will save you time like no tomorrow. I had a 262, and even though I only had 25-30 cases it was not much fun to replace them.

Most BR shooter go a bit smaller than .272 to get the snuggest fit in the chamber and throat.

Can also look at Sako USA PPC, the brass is a bit thinner, .270 if I recall

Very valid point by Icepick, my post is reated to the 6ppc

I do shoot a 6BR as well. I do not turn my cases.

 

[Obtunded]

There are also different 6mm barrel bore diameters... .236 and .237. Many PPC shooters and those using lighter bullets prefer the .237 bore, whereas most 6mm BR and heavier bullet shooters prefer the .236 bore.

There are many that use .237 borees for everything, but the .236 is SAAMI spec.