I play with 52/53 grain match bullets. 20.6 grains of H-4198 shoots 1/2" groups from my Winchester Model 70. The nice thing is it works in carbine length gas systems just fine. You might try 25.5 to 26 grains of WW-748. 24.5 to 25.0 grains of IMR-4895. H-322 will work from 23.0 to 24.0 grains max. The faster powders fall off the charts once you get over 55 grains in bullet weight. They usually will shoot really nice groups with light bullets but not very high velocities.
Your Benchmark load sounds good. I've noticed at least 200 fps increase from 16' barrels to 20" barrels in .223. That would put you around 3150 fps from a standard barrel. The gov. loads their ammo for maximum velocity, I wouldn't try to duplicate their loads with canister grade powders. I've also noticed that published velocities are rarely accurate. They are usually overstated by 50 to 100 fps. Shoot real M193 or M855 over a chronograph and it's almost always slower than advertised.
Your Benchmark load sounds good. I've noticed at least 200 fps increase from 16' barrels to 20" barrels in .223. That would put you around 3150 fps from a standard barrel. The gov. loads their ammo for maximum velocity, I wouldn't try to duplicate their loads with canister grade powders. I've also noticed that published velocities are rarely accurate. They are usually overstated by 50 to 100 fps. Shoot real M193 or M855 over a chronograph and it's almost always slower than advertised.
