Gun powder, it shoots similar to imr 8208 in my ar15 223, it looks like H335 to me but it's more accurate in my gun. I've been told that it's army surplus powder. 23.1 gr with 60 gr bergers does good in the ar 223. I'm wondering how it would do in 22-250 but no load data and I'm not experienced enough to take off all by myself !