Hard to go wrong with a popular rifle. You're not going to notice much difference in performance once you've gotten the features you want. I reload for my rifles and my friends' as well. Remington, Savage, Ruger, Kimber (I'm partial to the cosmetics of the 700)--they're all good performers from my experience. The 300mag has very manageable recoil. A lot of today's rifles are already equipped with recoil pads which work wonders. I can't tell much difference in recoil between my 7mag that came with a pad and my 25-06 that doesn't have one.

Distance shooting can be difficult. I can say that a 6" orange target looks mighty small at 500 yards through a 12x scope, and even difficult to locate in a 9x. As big as a deer or elk's vitals are though, it's not out of reason to gain the talent to hit this. 400yds is about the breaking point in 'ease' I'd say. After here, most full-power loads start dropping substantially and accurate range estimation is a must. I'm from mule deer country, and most shots are about 200yds, and with any skill of stalking you can usually get within 300yds of a distant target. Regardless, there's nothing wrong with the bragging rights of having distance-shooting capabilities in your bag of tricks. It's the really close, or really long shots that are the best stories IMO.

Summarized-- you should be fine with any rifle you want if it has the features you like. It'll take practice and memorization, but long shots aren't impossible.