I just started loading for my 458 Lott (CZ550)and after reviewing various sources of data I started with AA2520. Has anyone had experience with this powder as to temperature sensivity or anything else. I loaded Hornady 500gr soft points and started at 81 gr and went up 1gr at a time. Velocity seemed to top out at 83gr at 2300fps. The 81gr ran 2224, the 82gr ran 2258, the 83gr loads were 2296 & 2300 and at 84gr the velocity dropped to 2274 & 2275. The accurate data lists 86gr as maximum. I brought the 85gr loads home with me. Any other loads that have worked for other 458 Lott owners?