tobnbr, having chrohographed M852 ammo with 168's from a few M14's, none of them went over 2560 fps at 15 feet from their 22 inch barrels. But the same ammo's shot just over 2600 fps from 24 inch Garand barrels. I've never seen a Remington factory barrel with as tight of bore and groove diameters as those M14 or M1 barrels had, so their velocities will even be lower. And velocity's gonna drop about 25 fps per inch going from 22 back to 20.
Would be interesting to see what the peak pressures are for any 20 inch barrel getting 2600 fps at the muzzle with Sierra 168's out of a .308 Win. case. Especially with any powder that'll shoot 'em accurate. But I agree that 2600 fps with the 168 SMK out of a 20" barrel is easily accomplished and 2700 isn't unheard of. Lots of folks load ammo way, way over maximum safe pressures.
Last edited by Bart B.; October 24, 2012 at 07:49 PM.