I've shot all of what you list, to put it in context, figure the recoil of your 777 load now instead of the whop bang it's just bang. Seriously recoil about the same you'll just notice the difference in how quickly it builds. While there is nothing wrong with the 300 WM, don't count out the 06, factory loads up to 220 gr ( if your willing to search/pay for it ) or if handloading you can really have fun. Will the 300 do anything the 06 can't, no it'll just do it a little faster. As far as a recoil pad goes I've put decelerator's on all of my rifles, I here the Sims is very good as well.