I had Pac Nor build two customs with the 10" twist and three groove barrels with a reamer with zero freebore. I got three shot groups with the bullets touching using about any 100g Bullet at 3800 fps+.
A gunsmith in San Diego gave me the idea when we were hunting with his built on a Mauser. It is really hard to comprehend just how flat shooting a 100g Bullet is at 3800+ fps with the extreme accuracy.
I know of 4 other guys that has used Pac Nor build them the same type of custom and they all are extremely accurate and fast.
Norma brass is soft. If you can find any PMC brass, it will last indefinately. I neck size till the forth or fifth firing, then full length size. So far, I have 12 firings on a case before the primer pockets get loose.
I killed two does with mine on a powerline at 325 yards with 100g Nosler Ballistic Tips. The first was shot and a total bang flop. A few minutes later, a second doe walks out and starts licking the first doe, bang flop right on top of the first! With a muzzle break on the rifle, I actually saw the water vapor fly off the deer...the rifle barely moved from recoil.
The 257 was Roy Weatherby's favorite cartridge...nuff said!
