Okay, I won't ask how, but we thought about this once the bullets became available for us wee mortals. I'd treat them like the 265 Hornady FP, starting them out with H335 or H4198, the 2 that worked the best for my .444, at maybe 1.5 grs under max and work up looking for the typical signs of borderline pressure. Hornady tends to be quite conservative in their charge weights and in both my .444 and .45-70 using their data I usually wind up with the most consistent speed and accuracy with no excess pressures whatsoever somewhere over their stated max. E.g., their max charge for a 240 gr XTP in the .444 is 46.5 grs of H4198 and mine likes 47.5. In a 300 gr XTP, book max is 51.3 grs of H335 but my best load is 52.5. Okay, how did you get 'em?.....hell, I had to ask.