Bouldersmith,
We do have some caps but it is a tedious process and probably not the final solution to producing these in any quantities. I too have some loads to test, maybe tomorrow. I need enough time to photo and chrono the event.

Marrakai,
Plastic would seem to be the way to go. I can't find my notes but I think nylon was half the weight of the metal cone. That has been just a part of the puzzle though. Untill just recently getting the velocity while keeping the pressures right had been a problem. The loads we are shooting now are a bit higher in pressure than the original cartridge but safe. Those Brits were on to something with their turbo primed loads.