6br freebore

[Wellington]

Yes I know this has been hashed over, I have studied the various threads and still don't have an answer in my head. I am getting a 6br built for bench work (for score). My smith says he has two reamers, a 0 freebore and a .100 freebore. I want to try the various berger bullets up to the 80 fb varmint/target. This includes the 68gr flat base target as well as the Sierra 70gr MK which is a boat tail. Will the 0 freebore work with the 80 gr fb berger? The twist is 12 if that matters. Thanks for your patience.

 

[madmixerman]

I would choose 0 freebore. I have one with 60 freebore and the 68 grainers are barely in the case.

 

[Mark W]

I have a 0 freebore 6 bra (same neck as a straight BR) and I can shoot everything from 55 grain up to and including Barts and Berger 80 grain bullets. That long neck is very forgiving.

 

[ckaberna]

I would vote “0” given your bullet weight choices and the twist of barrel

 

[Boatschool02]

Please consider searching for my full write up with pictures. I recommend NOT associating weight with freebore. What matters most is bullet length & profile. Very similar bullets (by weight) can vary by 0.100+ in ideal freebore. The flat back Berger 80 and the boat tail Sierra 70 couldn't be more different in this respect.
Fortunately, the 6br neck length is very generous. Many different opinions on ideal engagement in the neck, mostly between competitors looking for raw performance vs those looking to wring out max barrel life. Freebore length can also vary based on throat angle and case overall length. A good Smith can extend the zero freebore to suit your bullet of choice. If starting new, I'd pick one premium bullet that you can get enough of for the entire barrel life and learn to tune powder and seating depth, etc. Provide a dummy round to your Smith or reamer manufacture and start out with an ideal solution instead of a jack of all trades compromise. IMHO, there's more optimization to be had, learning bench manners, reloading practices, and load tuning than swapping between off the shelf bullets.

 

[Dgd6mm]

Ogive is what matters.

 

[NorCalMikie]

Zero free bore. Nuf said.
The throat will get longer, faster then you might expect.
Start with 55s or lighter and go heavier as the throat gets longer.

 

[Webster]

Yes I know this has been hashed over, I have studied the various threads and still don't have an answer in my head. I am getting a 6br built for bench work (for score). My smith says he has two reamers, a 0 freebore and a .100 freebore. I want to try the various berger bullets up to the 80 fb varmint/target. This includes the 68gr flat base target as well as the Sierra 70gr MK which is a boat tail. Will the 0 freebore work with the 80 gr fb berger? The twist is 12 if that matters. Thanks for your patience.

Definetly the 0.00 free bore. I have 0.030" FB. I shoot lighter bullets but a 70 gr is only about half way down the neck. Can your gun smth tell you how far an 80 gr is in the neck at touch 0.00 and 0.100" FB? Someone on this website probably has the answer.