I had two Weatherby Mark V in 257 Weatherby, increasable killing ability on this round with the factory 117 Ornx bullet I believe. Friend kIlled 6 bull elk with his Mark V. Then I met a gunsmith from San Diego that had a custom 257 with zero freebore and was shooting the 100g Nosler BT and Partitions at 3850. We shot the barrels out in 1600 rounds on chucks and coyotes. We got extra barrel life, due to the fact that the zero freebore added extra barrel life. Then I had PTG grind a reamer with zero freebore, and over time wore out 5 barrels shooting the 87's at 4130 and 100's at 4000 fps on a 30" hart bbl, with 26" Harts giving 3850 with the 100g bullets, and surprisingly, the 100g Partitions shot half inch groups.
With a Gentry muzzle break on a 26", #5 contour that I now have, you see the water vapor fly off the deer's opposite side as the bullet exits...so little recoil you see the animal collapse. I have never had a deer run when shot within 250 yards with this caliber...never.
Rock chucks detonated like a paint ball splattering on a black rock, and coyotes were cut in half at times.
I always shoot R#22 with 215's with 100g-117g Bullets, 3850-3600 respectively.
