Colorado,

First, the 500BPE was not a DG cartridge. PB DG rifles really started at 10 bores. I'd love to provide a great quote but I'll have to do it later since I am short time this moment.

Second, there is nowhere where I am contradicting myself. Energy is a nearly meaningless number, IMO, since you can get plenty of it by dropping bullet weight and increasing velocity. This formula is a recipe for lousy penetration and poor bullet performance. Momentum is a better number to use since velocity is not squared in the formula and thus greater emphasis is placed on bullet weight. Bullet weight and constuction are everything for penetration; but it is bullet weight FOR CALIBRE!

You need no less than 450grs in 458, IMO, 480 is fine and 500 better yet. Really we are talking sectional density since we are talking bullet weights and calibres. The old English standard of no less than .300 is still a good rule, IMO, though there is some possibility that modern large flat meplat bullets perform well enough to shave a bit off the .300 figure. Then you will need enough velocity to provide the bullet chosen sufficient momentum to ensure penetration.

In a Rush,

JPK