The 9.3 cartridge I am talking about is the .366DGW which is a direct neck down of the .416 Rigby. I found I could push those 300 grain Swift A Frames at 2900 FPS with this cartridge at a pressure level of 49400 CUP and that is substancially faster then Swift intended them to go. I only recovered three bullets Two of those recovered were from Gemsboks and they weightd 292 and 295 grains. The third bullet was a finishing shot on a Zebra. This bullet went through about 4 feet of Zebra and a foot or so of sand and it still weighed in at 275 grains. I do not think one can go wrong using the A Frames.