My 338-06 was purchased used. It has a MKX action with a 24" McGowen barrel. I use 4320,4064. My best accuracy loads are:

225 Horn SP 51gr 4064 Fed cs,RLR prim

200gr Horn SP 52gr 4320 or 52gr 4064 "

210 Nosler Part 52gr 4320 RP CS., WLR prim

I got these out of "Wildcat Cartridges" and they all shoot 1" or less in my rifle. I have only used Fed & RP 06 cases run in a 338-06 FL die with a tapered expander. Be sure to lube the inside of the neck well, and they go very smooth.

art