Have bought a Lyman mold 311332 GC two cavaty mold. It throws a bullet that when lubed and the GC applied weighs in at 194.5 grains. Lyman states it is a 180 grain bullet, but they also used to produce a 311334 that is nearly a dead ringer for the 311332. I really don't have a problem with the finial weight but would like to start out with a powder that is suitable for accuracy with this bullet in a 308 Winchester ( 1 in 12 twist barrel). To start with I tried the Lyman hand book accuracy load of 5744 at 21.0 grains. This produce 4 1/2" groups at 100 yards. The rifle that this is being test fired in has a Hart barrel and will shoot sub 1/2 MOA all day with jacketed bullets. The cast boolits test fired are inspected by eye and weighed to within + or - 0.2 grains, and sized to .309. The next powder I tried was Unique at 11.0, 12.0, 13.0, 13.5, and 14.5 grains. The 13.0 and 13.5 grain loads produed the smallest groups, but there was vertical in them. The avg. was about 1.5 to 2.0 inchs at 100 yds. However at 200 yards there was clearly two grouping to the same load that were vertical. I'd get 2 shots touching high and three shots touching about 3" lower. The chronograph showed this in the spread of velocity. So I'm looking for a powder that has proved to be of the best burning rate for CB with GC at around 1400 to 1600 fps. Anyone have any suggestions based on their first hand experince with a powder that should burn clean and have a low shot to shot spread in velocity?
Thanks, Sendaro