I have been testing my 338 RUM for a couple of months, I have had good luck with Hornady 225gr SST's and Reloder powder. I am getting right at 3100-3150 fps and under 1.5 inches at 200yds. My rifle is heavy, a Shilen #7HV barrel, Remington action, Leupold long range scope
and McMillan stock.
I've been fiddling with different bullet weights and powders to see what the gun likes. It is a heavy rifle and running 30-40 rounds thru it is no problem. I'm not a big brake fan but this gun has one. It is not as bad as some types but it is still loud and makes earplugs a must, especially when hunting.
I went with the 338 RUM for a couple of reasons. 1. it easily duplicates 338 Lapua and fits in a long action without mods. 2. the cartridge has no belt, rebated rim or any other odd feature of some large cartridges.
Recoil for a few shots at some critter is never a problem for me. I built this gun a bit heavy because I wanted to be able to run quite a few rounds through it without suffering. In all honesty it is about as hard as my .308 chassis rifle.
I am planning on hiking into a mostly flat mule deer area and using it past 800yds. Every deer I have scene in this area is so far away it is not funny. The good news is that some of them are quite massive.