I have two buddies that have 338's. One has the ruger model 77 and the other has a tikka T3. The ruger shoots almost anything good but the T3 is a little more picky. They both shoot Federal 250gr very well. I worked up a reload for them that they both shoot very well also. It duplicates the Federal 250gr.
I would think that partition would be about perfect..I'm not sure how fast you could drive one out of that little case without blowing the pressure skyward but it would still take out any animal in the state you could hit with it.