Recoil is all about Newton's "equal and opposite reaction". The faster you send something squirting out the muzzle and the more that something weighs, the more recoil energy you'll have come back at you.
Similar to the way you feel more impact colliding with a large person versus a child, so goes recoil. Small guys tend to roll with the recoil more than heavier shooters who have more inertia. For example, LPR is a friend of mine and my 416 Rigby was no problem to him off hand. On the other hand, having 60 lbs on him at that time, I soaked up a lot more recoil. That said, I would recommend that you make friends with someone with a 300 and shoot it a bit from sitting, kneeling and especially prone, to ensure that you know exactly what you're getting yourself into. You'll know after a couple decent range sessions.