Should I be Concerned?

[Williamb]

I just received delivery of my new and first 6mmBR. I had it custom built and it took quite awhile to receive.

I had specified a .272" chamber as I plan on using Lapua brass without wanting to turn the necks. The spec sheet that came along with the rifle indicated the chamber to be .271". Somewhat surprised since I discussed a .272" chamber with the smith as well as in writing.

Am I winding myself up over nothing? Will there be a difference once I start reloading and chambering rounds? Or would you send it back to get it corrected at the smith's expense?

Looking forward to your comments.

Thanks

William

 

[6BR]

William, you will be fine. Your Lapua brass will measure, with bullet seated, .269 so that will give you .002 clearance which is actually perfect. All my loaded brass measures .269, so you will be fine.

 

[Williamb]

Thanks for your response. I assumed I would be but nice to hear from someone with experience with this caliber.

 

[NorCalMikie]

I just went out and checked my loaded rounds. They measure .268 to .2695. Mine is a .272 no turn neck chamber so you should be good to go. Now go pop some rounds.

 

[DMAC67]

William,

Just wanted to and another assurance that the feed back you are getting is spot on. I have had two 6mmBR custom rifle over the past 4 years and actually shot one barrel out,4800 rounds). Both were no turn chambers and I only used lapua brass. All loaded rounds were .2685 to .269".

When I ordered my reamer I got a .272" neck because I was paranoid about having enough clearance on a loaded round,this gives me .003 clearance on a loaded round). I now wish I ordered a .271" as .002" clearance is more conducive to accuracy and longer brass life. So you actually lucked out with the .271" chamber !

 

[cwood3]

Not wanting to hi-jack the thread, DMAC, what part of Houston do ya live in? I'm just down from Tomball,shoot 6mmBR as well).

cwood3

 

[Mark Walker in TX]

Not wanting to hi-jack the thread, DMAC, what part of Houston do ya live in? I'm just down from Tomball,shoot 6mmBR as well).

cwood3

Sorry for the continuing hijack, but CWood, if you are shooting a 6BR you should come and join us at Bayou rifles on Sunday for the 600 yard prone match. It is a fun match. I bet DMAC will be there as well...

To the OP, I have a 6BR-DX no turn, and it is a .271, and it works great! You will be fine with it!!!

Mark Walker
Houston

 

[mwood]

I wish I would have seen this post a few weeks ago.
I was told by a gunsmith that I should turn my necks lightly, as he said a Had a "minimum spec" neck/ chamber. When I called the factory, and Pacific tool, I was told it was a shade over .271
When I measured my loaded Norma Brass, it was indeed about .270
So I went through the learning process of turning the necks.
The only reason I was using Norma, was that was what was available at the time. I just recently finally was able to get some Lapua 6br brass. And after reading this thread I just seated a Berger 70 grain to see the diameter. And "Presto"
a .269 neck without turning. So I am now assuming the solution is to simply use Lapua brass, and that having a .271 chamber is a good thing?....

Also I noticed it took a bit of pressure to seat bullet,Wilson seater), so I may have to use an small amount of expansion arbor for new brass.
I think the final outside neck dimension,.269) should be the same regardless of the fact that it is a combination of the expansion and the bullet, instead of just the bullet doing the expansion?

 

[mwood]

does not anyone have advice for my above post?
,thats what the question marks are for)

 

[vmthtr]

Michael,
Use the Lapua brass and don't worry about turning necks. Seat the bullet and let it expand the case for the first time. I am assuming you are using a bushing type die for resizing after forming to chamber? ,I use a 266 busing for mine, I think would have to check to make sure)

Mike

 

[mwood]

VMTHTR....thank you for your reply......
I appreciate your input.
I did what you said last night with Lapua Brass....
much nicer than Norma.
Because the I.D. was a bit small,new brass) I first used a .243 mandrel, which put the I.D. at about .2425.
I could not use a bushing die because the I.D. was already too small / tight bullet tension...thats why the mandrell approach for the new brass.
This gave me a perfect neck tension with a Wilson seater.
The final Neck O.D was .2685 to .2690, which is perfect for my .271 Chamber on my Cooper.
Once this Brass is fired, I will then use a Redding Bushing die in the normal fashion, to come back to the same demension. Most likely a .268,but I have other sizes if required)
Sure do like this Lapua Brass!
Again, thanks for input, nice to know I don't have to turn the brass!