The 400 Hammer does look very interesting.

I also have some 380 grain Lehigh copper flat points. Originally purchased for 45-70 use. I have not measured the length. By eyeballing they look equal in length, or very close to, the Cast Performance 460 grain flat points.
The Lehigh 380 grain at least looks as though, that it would slap the snot out of anything in North America.
Whether fired from 45-70 or 458 Winchester.