6BR, throat length for 80 grain bullets

[knightsniper]

I am building a 6BR rifle, I want to use berger 80 grain fb varmit bullets, what is the best throat length using these bullets?

 

[gunsandgunsmithing]

I am building a 6BR rifle, I want to use berger 80 grain fb varmit bullets, what is the best throat length using these bullets?

For the 80gr fb bullets, .080-.100" will work very well. The long neck of the BR is pretty forgiving in this regard.

 

[JamesnTN]

I believe I went with .075

 

[boltfluter]

.080 works great for me.

Paul

 

[Eric Leonard]

10 twist and faster I would go .104 and 12 twist and slower I would go zero freebore..

 

[BartsBullets]

10 twist and faster I would go .104 and 12 twist and slower I would go zero freebore..

Big

I'm curious why you feel the twist rate would require a different freebore for a given bullet?

Bart

 

[Eric Leonard]

Big

I'm curious why you feel the twist rate would require a different freebore for a given bullet?

Bart

just that if I am using a 12 or slower twist I will be using bullets that will work very well with a zero freebore and if I am using a 10 or faster that the bullets I would be using would work well with a .104..

 

[knightsniper]

For all who is concerned ,my
build is with a 12 twist barrel.

 

[Dstroud]

For all who is concerned ,my
build is with a 12 twist barrel.

For barts 80s fb or bt 80 to 100 will work great on the 80 grain bt the bearing surface at the base of the bullet is over half way down the neck

 

[Dstroud]

I am building a 6BR rifle, I want to use berger 80 grain fb varmit bullets, what is the best throat length using these bullets?

The berger 80 fb have a lot of bearing surface, don't go too short

 

[NCVarhtr]

All zero freebores are not exactly alike. I have a 6X47 Lapua with zero freebore and the base of the 80 Gr Berger fb comes almost (within a few thousands) down to the neck/shoulder (donut) junction. So--based on that reamer configuration, about .040 to .050 would be about right for me. BTW, the 80 Gr Berger is a solid bullet-shoots great and kills extremely well. Good luck..

 

[Brett S]

Here is a 80 gr Berger with a 104 freebore. Be your own judge.

 

[Brett S]

6BR Improved with the same neck length as a BR

 

[hrlincoln]

6BR Improved with the same neck length as a BR

Looked at your picture and have a couple questions.

Is your lead angle 1-30-0?
Where is the 80 with respect to the lands, i.e. .010 off, .010 in or??

Thanks

 

[urbanrifleman]

I am starting to think that .080 thou would work for everything except if you want to shoot 55 grain varmint bullets at the lands. Dave Kiff spec'd my reamer at 125 thou for 108 Bergers and while this works fine it is really way too long for 6Br and is more appropriate for Dasher with the 108. Even with 125 thou I can easily shoot 80s and 70s at the lands, but the bullet is pretty far out there.

I also think that a 275-276 thou neck would keep the donut from forming on no turn brass. I am really not sure the advantage of these tight necks. They seem to cause more trouble than they fix.

 

[Dstroud]

The angle is 1-30,the bullet is just at touch making a very small mark when shined with fine steel wool

 

[gunsandgunsmithing]

I am starting to think that .080 thou would work for everything except if you want to shoot 55 grain varmint bullets at the lands. Dave Kiff spec'd my reamer at 125 thou for 108 Bergers and while this works fine it is really way too long for 6Br and is more appropriate for Dasher with the 108. Even with 125 thou I can easily shoot 80s and 70s at the lands, but the bullet is pretty far out there.

I also think that a 275-276 thou neck would keep the donut from forming on no turn brass. I am really not sure the advantage of these tight necks. They seem to cause more trouble than they fix.

The only way a doughnut hurts anything is if you seat bullets at or below it. With all of your scenarios in your post, none should come close to it.

I agree that about .080-.100 works with a wide aray of bullets in a 6 BR. The long neck makes it very forgiving. I think you hit the nail pretty well on the head. You can shoot 65fb-105 bt bullets in a .100 freebore 6BR, very well.