I know these bullets are made with thin jackets so that they will expand at very low speeds but I want to push them at max speeds in a 458 Lott just for the sake of getting a feel of heavy recoil to work up my tolerence. I want to start out with them at around 2200 and then start moving on up to probably over 2600 fps. I'll just be shooting target with them so I'm not concerned about them exploding on impact but are the bullets capable of withstanding the speeds and pressures without causing any problems like jacket separation or anything else like that ?

I don't think you will have any problems. I have taken the Rem's up to the low 2600's out of a 450 Ackley Mag with no problems. AA-2015BR proved to be the most accurate powder I tried and gave an average velocity of 2601 fps out of a 26" barrel. Hope this helps tank.

Thanks, that's the info I was looking for.