In the words of another guy on this forum which I really liked.

Quote from gregwth7mmmag
Asking how bad an Ultramag kicks and how loud it is, compares to asking the price of a Rolls Royce. If you have to ask, then you probably cant handle it,lol. Its like touching off two 30-06 rounds at once, in the same gun. Very loud, it rattles a friend windows down the road from the range. Ive had great luck with accuracy of factory loads thus far. Ive shot my best groups with this gun. It can be painful to shoot at times, but then I didnt buy it for it not to kick!

It really isn't something to worry about. Its really all in your head. I see 160lb guys that shots 460weatherby that goes to Africa regularly. They do it, and don't think about it. Me, when they offer to let me shoot, I think about it. Therefore, it hurts. And I usually only shoot one, maybe two rounds. Before buying a 300RUM, find someone to let you shoot theres. You will be surprised. I have really light 30-06's that kicks compariably. It does have to do with the butt of the gun. In my head anyway.