Tim Sundles has an 18"-barreled .458 WM custom rifle that produces 4 fps greater MV than his 22" factory M70 rifle, both with same Buffalo Bore 400-gr TSX load. The custom has a Marquart barrel ... and maybe a .458 WM Special reamer was used to cut the chamber ? I doubt that a mere difference of internal barrel finish (as Tim guesses) could make that much difference. Any difference with 0.458" versus 0.459" groove diameter is minimal regarding pressure and velocity. Twist rates of either 1:10" or 1:18" make no significant difference in velocity and pressure, compared to 1:14" standard.
Ron aka "Rip" for Riflecrank Internationale Permanente NRA Life Benefactor and Beneficiary .458 Winchester Magnum, Magnanimous in Victory THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.
