Bob, great post but I don't think the necked up 300 H&H is going to do anymore than a 338 win mag will do (let alone the 340 wby). The taper on the 300 H&H will reduce case capacity and equal that (86 grains of water for each case) of the shorter 338 win mag: Thus no gain. Except for the fact that it will be a little slicker feeding...
