been loading the snot out of 300 bo super sonic using the 130 rcbs gas check mold. Im getting low on 110 and wc297 but have 5 jugs of wc820. Figured id give it a try but couldn't find loading data anywhere. So I used a bit of common sense and started with 15 grains. Groups shot were 5 shots at 50 yards. Guns were a 16 inch and an 8.5 inch ar15 both budget psa guns. The 16 inch gun shot 3/4s of an inch which was the best cast bullet load ive had in that gun. It didn't lock back on the mag though (probably because I have a 4.7 once buffer in it. 8.5 inch gun did just over an inch and locked back fine. At 15.5 groups opened up about a 1/4 inch and both guns locked back but primers were just barely starting to flatten. At 16 groups opened up about 3/4s of an inch and primers were flattening but not dangerously so. So I went home and loaded some up with 15.3 and it shot just was well as 15 in the 16 inch gun and actually better then anything in the 8.5. It kind of showed me that 820 definitely will work (and by the way aa9 is the same powder) but it has a narrow charge weight between what is to light and what is to hot. One odd thing I found with it was with 110 and wc297 ive shot the same bullet without a check on it and groups ran around 3 inch. Not great but still probably good enough to pound steel targets. With 820 I couldn't even keep that bullet on a 8x11 sheet of paper at 50 yards with any of those loads.
