Ive been using the standard version since 1988 in three different rifles. In a nutshell, the lighter bullets (210 gr and under) seem to respond well to medium rate powders, 4895, 4320, 4064 etc. You wont be able to get enough 4350 or slower in the case to get velocities much over 23 or 2400fps. The 250 gr bullets work good with powders like 4350, H414, and H380. One thing I have found is that this cartridge isnt a 338 mag. It works better at moderate velocities most of the time. Driving 200 gr bullets at 2900 is within the capabilites of the cartridge, but accurate loads are much more easily found around 2700 fps. 250 gr bullets seem to work best about 2400 fps in the guns I have used. This fall, I have been using the 185 gr coated x bullet at 2800fps with excellent results. So far I have shot four whitetails with them and two of those deer fell towards me at the shot. I like that kind of performance. One of them was at 320 yards and the other three were all close shots. Contrary to what some people believe, you dont have to drive a bullet at escape velocity to make a good killing load. Good luck with your 338.