Vic,
How about rechecking your figure for head diameter.You wrote it is .4365, did you mean .4653, or .4635".If so, 9.3x74R cases would work after trimming. If not,you are back to 9.3x72R, but it seems hard to come up with a bottlenecked case for a .366 bullet in a case with .437 head,considering case thickness,etc,and the statement that it is "obviously" bottlenecked.Your groove diameter seems made to order for my favorite H&G 512c bullet, 210gr blunt nose, .368 as cast dia.
Mike
Last edited by Der Ami; 02/14/15 09:53 AM.