You might want to check on a Sims recoil pad I ordered one for my 30/06 Mtn rifle but at that time they didn't have one to fit,said it would be later.It probably would be cheaper and better than any porting.Don't quote me on the % of recoil drop but I think I saw about 70% just don't remember.

http://www.hunting-pictures.com/memb...ght&encore.jpg