Outdoorslover, if you are shooting 3.5" at 100 and the same at 50 yards, that tells me You need to float the barrel. My x-150 used to be odd like that untill i used these shims and lifted it a tad. Go do the paper test and see what it will do. With these shims i used, theres no cutting or anything involved, just put the proper size hole in the shim and add one under teh front and rear lug, put it together and see if it will pass the paper test, if not, remove the barrel, add 1 more shim and so on. I used 3 shims but this brass shim im using is fairly thin. Im betting if you use these, you're going to get great accuracy. I went from 2" @ 100 down to 1" at 100 yards with that huge buick.. ahem, i mean with that huge bullet i am shooting. Heres a pic of my stock with the shims. I added a little rubber cement around the edges to hold them in place when i remove the barrel. Outdoors, if its a trust issue, point to someone in the board that you do trust and i can send it to them and then they can send to you. I honestly think these will help shrink your groups.