Help with an older 6br rem chamber

[Webster]

Yes, I'm aware of the differences. What I have is a 6mm BR Remington, the precursor to the 6mm BR Norma which is also commonly known as the 6mm BR or just 6BR and which has a longer COAL than the 6mm BR Remington. The 6mm BR Remington is considered to be obsolete by most modern 6BR shooters, but since I'm only shooting at 100 and 200 yards, the 6mm BR Remington with the 14 twist barrel is perfect for what I want to do. The attached test target came with the rifle, and although it was only a three shot group and shot only at 50 yards the group is still pretty impressive.

Thanks.

I shot a 6mm Rem for many years and killed 100s of GH with it. I consider it the equivilent of a 243 Winchester. It's a good long range cartridge but a barrel burner. If you ever rebarrel I would consider a Bertlein or Kreiger barrel in 6BR Norma or a 6BRX which has the same ballistics as a Dasher.

 

[butchlambert]

I shot a 6mm Rem for many years and killed 100s of GH with it. I consider it the equivilent of a 243 Winchester. It's a good long range cartridge but a barrel burner. If you ever rebarrel I would consider a Bertlein or Kreiger barrel in 6BR Norma or a 6BRX which has the same ballistics as a Dasher.

I believe he is saying 6mm BR Remington, not the 6mm Remington.

 

[group therapy]

 

[butchlambert]

 

[divingin]

I wonder if I can calculate the bushing size based on the neck thickness of the Lapua case, but I don't know what that thickness is. Or is there another way to calculate the bushing size?

Your final sizing diameter should be:

Bullet diameter + 2 x (the case neck wall thickness), minus a thousandth or two or three for brass springback

My last batch of Lapua 6mmBR Norma brass ran about .015" for neck wall, so:

.243 + .015 +.015 = .273, then subtract a bit for springback yielding about .270, .271, somewhere in there.

Given that you want the neck a couple thousandths smaller than your chamber neck, it sounds like you may need to turn the necks just a bit and go with a slightly smaller bushing. You do need to verify the measurement of your brass before proceeding, though.

Hope this helps.

 

[khoffx2]

Your final sizing diameter should be:

Bullet diameter + 2 x (the case neck wall thickness), minus a thousandth or two or three for brass springback

My last batch of Lapua 6mmBR Norma brass ran about .015" for neck wall, so:

.243 + .015 +.015 = .273, then subtract a bit for springback yielding about .270, .271, somewhere in there.

Given that you want the neck a couple thousandths smaller than your chamber neck, it sounds like you may need to turn the necks just a bit and go with a slightly smaller bushing. You do need to verify the measurement of your brass before proceeding, though.

Hope this helps.

Divingin,

Thanks for your input. I received the following reply from Lapua concerning neck wall thickness of new Lapua 6mm BR brass.


"Ken,

For the 6BR Norma LAPUA brass, the neck walls measure right about .012 thickness. So, .012 x 2 = .024 plus .24= .267 across the neck of a loaded round.


Take care,

Philip Hoham
Technical Support
Capstone Precision Group, LLC"

Thanks,

Ken

 

[newbieshooter]

Divingin,

Thanks for your input. I received the following reply from Lapua concerning neck wall thickness of new Lapua 6mm BR brass.


"Ken,

For the 6BR Norma LAPUA brass, the neck walls measure right about .012 thickness. So, .012 x 2 = .024 plus .24= .267 across the neck of a loaded round.


Take care,

Philip Hoham
Technical Support
Capstone Precision Group, LLC"

Thanks,

Ken

I just measured some new Lapua 6BR brass and I get closer to .013 neck thickness (on average).

I also loaded some dummy rounds with 2 different bullets (using the same measured brass) and get a loaded round diameter of .2685 and .269. I usually use a .268/.267/.266 bushing - depending on which shoots the smallest for a particular barrel. YMMV

 

[khoffx2]

Newbieshooter,

Thanks for the info. Based on Gunsandgunsmithing's recommendation and Lapua's response to my neck wall thickness question, I purchased .267 and .268 bushings for my die.

Thanks,

Ken

 

[Infrequent Shooter]

You should really eliminate your future headache and get somebody or cooper to rechamber that

I tried to find a recent thread but....
Aside from the twist issue, starting with a 6BR Remington, with 266 neck, what would be involved in rechambering to 6BR Norma? And maybe bolt face issue? Specifically, an older 40-x factory with the above specs.

 

[Webster]

I tried to find a recent thread but....
Aside from the twist issue, starting with a 6BR Remington, with 266 neck, what would be involved in rechambering to 6BR Norma? And maybe bolt face issue? Specifically, an older 40-x factory with the above specs.

This original post is 3 tears old.

 

[Infrequent Shooter]

like I said, I tried to find a recent thread