Tinker, you did catch that I was a teenager when I worked those loads up, right? Teenagers have never been known for their common sense. I was working without benefit of a chronograph, and didn't know the technique of measuring expansion rings of cases to judge relative pressures.

Even annealing the necks, brass life was short. (I had what I suspect was the only "small base" 458Win sizing die in the state, and used it often.) Most of the loads were worked up with surplus powders, usually 3031 and 4198 or equivalent "data powders". A drop tube was used to get more powder in the case.

The bullets were typically jacketed 45 pistol bullets, bumped up to .458" with a cannelure added. Bullets were given a _firm_ crimp. FMJs performed better than the lighter HPs; I was never sure if that was due to the weight, the length, or the thicker jacket.

Ball C was a lot more consistently accurate, but velocities were lower. If I were going to do further light bullet/high velocity experiments with the 458, I'd look at powders in the range of 2230 to BLC-2.