87 grain Speer TNT w/56.0 grains of H4350. It stays well within .5" and some under .3". Note my rifle only has 1 in 10" twist so anything over 87 grains shoots about 1.5"
JLAMB- 10 twist should stabalize even 120 grain bullets. your bullets are not keyholing are they? the 1.5 inch groups are due to something besides twist rate.