6mm BR Freebore

[Longtrain]

How much freebore do you need to shoot 105-108 class bullets in a 6 BR? Reamer has .100, is that enough? Usually jump bullets ~.025. Thanks.

 

[rkittine]

I asked the smith that built my 6mmBR Norma, what free bore I should have for 105s and between him and my mentor, they settled on .110. From what I am learning it is always easy to increase it.

Bob

 

[Dan Hall]

On my 6 BRs .100-.104 freebore that's on most reamers seems to work well with the bullets I shoot, 103 Vapor Trails. Some of it depends on how much of the neck your die sizes. It is my understanding that you want the heal of the bullet within that area the dies sizes. Good luck.

 

[tn6br]

How much freebore do you need to shoot 105-108 class bullets in a 6 BR? Reamer has .100, is that enough? Usually jump bullets ~.025. Thanks.

My chamber has .098 freebore and a berger 105 vld .025 jump shoots great. The boat tail barely starts into the shoulder all bearing surface and most of the boat tail is in the neck. I can shoot 68 gr bullets with that chamber as well with plenty left in neck.

 

[Longtrain]

Seeing the long neck of the BR case, I felt that .100 would be fine. Thanks.

 

[Phil3]

My chamber has .098 freebore and a berger 105 vld .025 jump shoots great. The boat tail barely starts into the shoulder all bearing surface and most of the boat tail is in the neck. I can shoot 68 gr bullets with that chamber as well with plenty left in neck.

68s with plenty (of bullet) still in neck? I am new at this, but wonder if you can touch the lands with that bullet and .098" freebore? Phil

 

[tn6br]

68s with plenty (of bullet) still in neck? I am new at this, but wonder if you can touch the lands with that bullet and .098" freebore? Phil

This pic is a 68 grain Berger flat base Jammed .005, a guy I shoot ubr with set a factory class record at a hundred and two hundred yards shooting 64.5 grain Berger columns that were just barely still in the neck I think that was a 105 freebore. Whatever the Factory Savage 6 br 8 twist reamer is. As long as the bullet can't be easily pulled out of the neck with your fingers it will usually shoot okay ymmv.

 

[Boatschool02]

I'm a novice, but my reamer homework on the subject suggests that 6mm bullet weight and freebore correlations are NOT linear. Numbers below reflect Berger published Cartridge Base to Ogive #s minus boat tail lengths. (Zero for flat backs.) As you can see, the 68 Varmint FB and the 105 VLD are actually quite similar with regard to usable bearing surface in the the neck at jam. On the opposite spectrum, the 87 VLD and the 88 grain Varmint High BC FB are miles apart.

 

[comagutsa]

Im running 105 fb on my 6br with 105gr hybrids and 108gr.. with .015 jump . 100fb will be fine