Well I will be honest, I don't own or have ever shot a 338 RUM. I have shot a 300 Wby, 338 Win and I own the 375. I have found that on my little frame (6', 300 lbs) the wby and win has a sharper kick then the big push the 375 gives me. The other two seem to also have a faster kick, if that makes sense. I would imagin that the more powder in the 338 RUM would put it in the same catagory as the 300 wby and 338 win. If there is a place you can go shot them before you buy them, I would do that. Here is Michigan, Williams Gun Sight does.
Ron