6 BR , how long throat should I get

[DanS]

I am getting a 6BR Norma built. A 1-8 Shilen #2 contour for coyote hunting mainly. Will mostly shoot 55-75 gr bullets. But would like to try the heavys just for the fun of it. How much throat do I need? .020, .040" ?

 

[Texas10]

I made a dummy cartridge with a 105 A-Max seated to just above the neck/shoulder junction and gave that and my barrel to the G.S. and asked him to throat it appropriately. Can't get the A-max now, but I do shoot 105's of various makes.

I believe Shilen will do that for you if you send them a dummy round.

 

[R.Morehouse]

I have 100 FB on my BRA and have been shooting 105 Hybrids and 103VT's. Don't know if that helps you much but there it is......

Regards
Rick

 

[rkittine]

I shoot 90 - 105 grainers in my 6BR and have a free bore of .105

 

[rwj]

Shooting 105s, 8 twist barrel, .104 freebore...

 

[pacificman]

I have a 10 twist 6br with zero free bore and shoot 87 grain v-max with very good accuracy. With that said...if you decide to shoot longer/heavier bullet they will be
in the case a good bit below the neck.

 

[swd]

55-105 is tough range. The 55's can use zero and the 105's .100"+. .040" would be a compromise that would probably be perfect for the 75gr range.

 

[JFrank]

Mines a .093 If I'm not mistaken. I can run a 108 Berger no problem.

 

[HTSmith]

55-105 is tough range. The 55's can use zero and the 105's .100"+. .040" would be a compromise that would probably be perfect for the 75gr range.

This makes sense to me. I had a .060 and I could seat in the lands with 55's, but with not much bullet in the neck. I also could also just barely keep the heel of a 105 Berger out of the base of the neck. .040 would give you some room for throat wear with 55's but put the 105's past the "doughnut" area. Tough to have both those worlds.

Edit: The 55 Sierra's shot like buckshot out of my 8" twist. Hornady 75's shot very well.

 

[Ccrider]

Split the range in half and get two barrels a low twist chambered ideally to shoot light boolets and a fast twist chambered to get the most out of heavy bullets.

 

[ImBIllT]

Short free bores just make the bullet use up case capacity. Too long a free bore will make your bullet jump too far. If you want to use a broad range of weights, seat the lightest bullet you want to shoot to the depth that gives you your desired amount of bearing surface in the neck, or possibly the least amount that you would like(all heavier bullets will have more) set up your throat length from there.

 

[NorCalMikie]

Start at ZERO!! Load with the lighter bullets and go heavier as the throat wears. (and it will, sooner than you might expect) WTF??
Go with a long freebore and it won't be too long to before you can't even get close to the lands.
I load all my "6 BR" rounds with the bullets .010 INTO the land. 45s and 50s shoot bug holes for me. Up to 60s now and still all going into one hole.
Go long freebore and you'll be sorry. Nothing worse that reaching for your favorite bullet and you can't get anywhere close to the lands. PLAN AHEAD!!

 

[GSPV]

If you are shooting bullets that light, you don’t need a 1:8. If you are getting the 1:8 because you will at some point shoot the 105 class of bullets, you need enough freebore to shoot them.

I used to shoot a 1:10 with an 80 thou freebore to shoot mid-weight bullets like 80-90 grain. It was a great compromise.

 

[Deleted old_dood]

I am getting a 6BR Norma built. A 1-8 Shilen #2 contour for coyote hunting mainly. Will mostly shoot 55-75 gr bullets. But would like to try the heavys just for the fun of it. How much throat do I need? .020, .040" ?

it really depends on the shape of the bullet. I had a custom reamer made by JGS based on dummy rounds using the Berger 90g target BT. The freebore was about .040" with the bullet just above the NS junction with a .020" (or so) jump. When I tried out some 95g TMKs, with the same .020" jump, the bottom of the bullet bearing surface was quite a bit further from the NS junction. I didn't measure but I believe about .050" further than the Bergers.

 

[boltfluter]

.080 is a very good comprise. I get great results with an 87 V-max and the Berger 105 VLD. Also drives tacks with the Berger 95 VLD. Very versatile length imho.

Paul

 

[Dusty Stevens]

Youll need a 13-14tw and a .030-.050fb to shoot those bullets. At the other end of the spectrum youll need a .120+ and 8tw to shoot most 103-105 bullets

 

[fm1947]

I am getting a 6BR Norma built. A 1-8 Shilen #2 contour for coyote hunting mainly. Will mostly shoot 55-75 gr bullets. But would like to try the heavys just for the fun of it. How much throat do I need? .020, .040" ?

Take a couple bullets that you're going to use, set them in case where base is at shoulder junction then you can figure out how you want your headspace send to shilen two dummies they will set a accordingly

 

[dreever]

I use a .060 freebore for anything from 55's to 105's. I primarily shot the Berger 105 VLD's in Ground Hog Matches with quite a bit of success.

 

[Murray Brook]

I use a .060 freebore for anything from 55's to 105's. I primarily shot the Berger 105 VLD's in Ground Hog Matches with quite a bit of success.

Could you elobarate a little on the "no trim to length" you use on your reamer. TKS
Like what are the advantages and disadvantage if any.

 

[dreever]

Could you elobarate a little on the "no trim to length" you use on your reamer. TKS
Like what are the advantages and disadvantage if any.

main advantage after twenty loadings I just throw the brass away when I get my first split neck. I don't anneal I've never seen the need.