IMHO you are fighting a losing battle, trying to make the rifle shoot a bullet it simply doesn't like, no matter how well made. Most .308s seem to like a bullet of 160 to 200 grains, in my experience, and there are more than one rifle (not just in .308) that you can't exceed 2000fps with cast. Who knows why, may be rough bore, inconsistent bore diameter worn/ oversize throat, etc etc. I have an old win mod. 670 with a very rough/ pitted bore that shoots the "cheapo" 180 Lee into 1.5" @ 100 with 31 grains IMR 3031 why who knows? Don't give up! 308 Win. is one of the best with cast as many have found. Larry g. is right, 4350 works great with heavier loads, this same rifle will put 10 rounds in 2.5" @ 100 with 40 gr IMR 4350 and a Lyman 311290(210 grain) or a Lee 200 grain. Not benchrest accuracy , sure, but great for deer -- velocity 1900-1950 fps. Odicoilius.