I am so sold on the .338 Win. that I will probably never change. If it recoils too much then the simple suggestion seems to be have your friend load it down to the same specs as the RCM...
I shot the 338-06 for a long time until I figured out that the 338 Win was so well balanced that it, with proper handloads, would do anything the 338-06 would do and a whole bunch more if the need arose...I also figured out the difference in recoil was next to nothing in my case.
But if one just needs an excuse for another rifle then thats a whole different ball of wax!
