May 27th, 2007

6BRX Barrel Life and Long-Term Accuracy

For the past year, Forum member John Skowron (John708) has been campaigning a 6BRX, built by Nat Lambeth (RustyStud). You’ll find the full history of John’s 6BRX project in this Forum Thread. With this rifle, John was the overall 1000-yard winner at Butner in February 2007.

6BRX 6BR improved

The 6mm BRX is based on the 6mm BR cartridge. The shoulder is moved forward, but the shoulder angle and case taper is the same as the parent cartridge. This way you can use standard dies for most purposes (although it is a good idea to have a custom full-length die so you can size the entire case body). Many of our readers have been interested in the 6mm Improved (BRX, Dasher etc.), but they’ve wondered about case durability and barrel life. John has answers for those questions:

6BRX Case Life
Case life running the Berger 105s at 3000+ fps is 14-15 reloads. Brass was discarded when the primer pockets became too loose. The 6BRX brass OAL after fireforming is 1.56″. Max OAL for the 6BRX is 1.58″. The brass never stretched enough to require trimming before discard. Anouther plus for the 6BRX and Lapua brass.

By the way don’t even bother with Remington-brand 6BR brass. The primer pockets were so loose after my standard fire-forming load I had to trash all the cases. Stick with the good stuff, Lapua.

6BRX Barrel Life
I now have 2570 rds through my 6mm BRX. I was just at the range today doing an accuracy test. I shot two 10-shot groups at 100 yards, one with 105gr Bergers, and the other with 107gr Sierras. Both were identical 0.44″ groups. Not bad for a rifle with 2500+ rounds through it.

Achieving this barrel life goal pretty much completes my 6mm BRX project. I’m now shooting a cartridge that has the same or better barrel life than the 260 Rem, it’s more accurate, with essentially equal wind drift. I’ll continue to post updates on barrel life. I think this barrel will last for another several hundred rounds.

Heavier Bullets
As far as shooting the DTAC 115s goes, I’ve temporarily abandoned that effort. The 105 Bergers, running 3050-3100 fps, give up very little wind drift to the 115s running at 2900-2950 fps. You might potentially get 3000 fps with the 115s using H4350 and throating the chamber to seat the bullets out. But since I very happy with the 105s and the way they’re performing at long range, I’m not going to change for now. [Editor’s Note: The Berger 105s in John’s latest reports were lot #559, from Berger’s new die.]

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