Have tried this powder briefly in my Hornet (as many have), but have now tried it in my 221 Fireball. Amazing! Using Barnes 40 gr Varminators, 16.5 gr of LilGun (CCI BR4 primer), had avg velocities of 3550fps in one rifle, and 3620fps in my new Classic 700. Load data is from Hodgdon's site, and there were no excessive pressure signs. Only oddity was sooty case necks, not expected with max loadings. Sure is an efficient cartridge and powder.
BTW..groups were 0.7 and 0.8" (5@100yds), typical for these guns with me driving.