Originally Posted by Wrcassell21
I am shooting a savage model 10 FCP in 308, 1:10 twist 24", 178 amax grouping 1/4" at 100 and like crap at 600 "well over ", I'm using 178 amax, 45.5 varget, and 2.815 oal, when max chamber is 2.825. love the speed (2720 ) but would like 1/2 moa better. think I'm shooting too fast ? any suggestions
I think your shooting too hot of a load. 45 to 46 grains of Varget is max for 155's in a .308 Win. case and that's a good load for Palma long range rifles.
With a much heavier bullet atop it, pressure's going to both much higher and get erratic. And while your bullets are leaving about 100 fps faster than normal loads with bullets of that weight at safe max pressures, they probably have a huge spread in muzzle velocity. A 100 fps spread in muzzle velocity for a .308 gives about 0.2 MOA vertical shot stringing at 100 yards. At 600 yards, it'll be 8 inches; 1.3 MOA. At 1000, 3.5 MOA or 35 inches. Erratic pressure curves also whip the barrel inconsistantly that may not be visible in the groups at 100 yards; just way down range a long ways away.
A better powder for bullets that heavy in a .308 case is IMR4064. About 43 grains has been used in competition with 180's that would shoot under 3 inches at 600 yards.