How much freebore in 6BR for light weight bullets?

[RussellJ]

Thinking of having a slow 12 or 14 twist 6BR barrel made to shoot light weight bullets 70-80gr. Barrel maker wants to know freebore needed.

Lefty;
This should answer your question:

http://forum.accurateshooter.com/threads/6br-freebore-pictures.3912264/#post-36855361

 

[Webster]

Thinking of having a slow 12 or 14 twist 6BR barrel made to shoot light weight bullets 70-80gr. Barrel maker wants to know freebore needed.

I have a 6br 14 twist for varmint hunting. 0.030’’ fb. 58 gr Vmax. With about 0.010’’ jump the bullets are about half way down the neck. Been a while since I loaded 68 & 70 gr bullets but I don’t think they are very far in the neck. If you get 0.030’’ fb your gunsmith can always give you more fb with a throating reamer. I would rather be short than to long.

 

[NorCalMikie]

I would rather be short than to long.

Short you can change. Long? Gunna cost you a re chamber.

 

[Mark W]

My 12 twist BRA has zero freebore. It shoots good with everything from 55 grain varmint bullets to Bart’s 80s.

 

[NorCalMikie]

And with VLD bullets, they'll be way deep in the throat. The shorter the free bore the better.

 

[prowler]

Thinking of having a slow 12 or 14 twist 6BR barrel made to shoot light weight bullets 70-80gr. Barrel maker wants to know freebore needed.

Just recently had a 6br built with a 14 twist. Shooting 68grn Barts ultra. Went with .025 freebore.

 

[Lefty Trigger]

Lefty;
This should answer your question:

http://forum.accurateshooter.com/threads/6br-freebore-pictures.3912264/#post-36855361

Great post with good info. Looks like I need a 12-14 twist with zero freebore for what I'm wanting to play with. I have got a few great PM's as well and thanks for all those as well, guys...

 

[Ackman]

To me, light 6mm bullets are anywhere from 55-70 gr. They'll go real fast and shoot flat and very explosive on small critters. This is where some of them seat in a ZERO freebore chamber. The split
neck case is set with little tension so these bullets are just kissing the lands. Here are a few seated in my 6BR - 14tw Hart, 0 freebore. You can see that even with no freebore the 70's aren't near the base of the neck, and 55's are pretty far up there. All these bullets are very accurate. But I like the 55's and 58's best on pd's.


70 BT






70 TNT







58 VMax




55 Sierra BK

 

[BoydAllen]

Nobody seems to have slow twist barrels and if they do that dont have a 0 freebore reamer or just flat out dont want to fool with it. To keep me shooting I ordered another 6,5x47 Lapua barrel from Shaw, was instock and shipped today so that will give me something to play around with till I can get a BR barrel found. Northland told me that Shilen is the only company they deal with that has that reamer but they are 20-25 weeks out! I'm 9 weeks in on my 7mm BR barrel now and its driving me nuts waiting. Just got a crap ton of 70gr Sierra match kings and Berger 80gr flat base bullet in,... just no barrel for them... Grrrrr.

That is why people buy their own reamers. BTW with a zero freebore reamer and a throating reamer a smith can make any configuration you want.

 

[BoydAllen]

To me, light 6mm bullets are anywhere from 55-70 gr. They'll go real fast and shoot flat and very explosive on small critters. This is where some of them seat in a ZERO freebore chamber. The split
neck case is set with little tension so these bullets are just kissing the lands. Here are a few seated in my 6BR - 14tw Hart, 0 freebore. You can see that even with no freebore the 70's aren't near the base of the neck, and 55's are pretty far up there. All these bullets are very accurate. But I like the 55's and 58's best on pd's.


70 BT
View attachment 1193778





70 TNT
View attachment 1193775

Back in the day, I remember that someone, who was using something like the football shaped Nosler 55 gr BTs had a reamer that was zero FB, with a 2 1/2 degree leade angle, to put more of the shank in the case. FYI the SAAMI leade angle for the .222 Remington is three degrees, ten minutes, and 36 seconds, paired with a .045 FB that is .224 in diameter. The reason that I mention that is that it has an excellent reputation for accuracy, and we get so wrapped up in the most common angle spec for custom reamers of 1 1/2 degrees per side.




58 VMax
View attachment 1193774



55 Sierra BK
View attachment 1193773

 

[AckleymanII]

Thanks for posting the pictures Ackman! Pictures tell all!

 

[Lefty Trigger]

That is why people buy their own reamers. BTW with a zero freebore reamer and a throating reamer a smith can make any configuration you want.

Thats exactly what I did, bought my own. 6mm BR with zero freebore.

 

[Evan]

Nobody seems to have slow twist barrels and if they do that dont have a 0 freebore reamer or just flat out dont want to fool with it. To keep me shooting I ordered another 6,5x47 Lapua barrel from Shaw, was instock and shipped today so that will give me something to play around with till I can get a BR barrel found. Northland told me that Shilen is the only company they deal with that has that reamer but they are 20-25 weeks out! I'm 9 weeks in on my 7mm BR barrel now and its driving me nuts waiting. Just got a crap ton of 70gr Sierra match kings and Berger 80gr flat base bullet in,... just no barrel for them... Grrrrr.

http://www.bugholes.com/product-p/x-6mm-13.5tw-ss-lv-24.htm

or from Brunos:

https://www.brunoshooters.com/mm5/merchant.mvc?Screen=CTGY&Category_Code=barrels_krieger_6

Several options there. Have it shipped to your smith to save an extra shipping charge.

 

[Bill Norris]

My 6mm BR has a 24 Inch 1 - 14 Twist barrel and the chamber has .055 freebore. I have loaded from 55 gr. up to 75 gr. bullets and all have grouped well with 68 gr. Bergers @ .010 off the lands giving the best group so far.