Kick Eez - grind to fit pads are awesome. I have them on my 300WM, 338LM, and 50 BMG. They are the biggest difference maker in reducing shoulder soreness by the end of the day.
For actual recoil reduction, I've found nothing better than Limbsaver. I have Pacmayr & KickEEZ too, but if I were trying to tame a magnum, Limbsaver would be it.
Pachmayr Decelerator, by far the best, longest lasting and most importantly not too soft. Sims has there place and I am quite fond of them on lighter calibers, but not on the big ones!