I just went thru this with a new condition xbolt in 6.5CM - its a design flaw by Browning in their xbolts, certainly not an easy mounting system, they dont need 8 holes to secure a base or bases on a hunting rifle.!
They will work - but you need to know about the cross threading and breaking screws issues ahead of time, be careful when mounting. Unfortunately for me the damage was already done by previous owner.
2 Leupold base screw tips broke on the way out of mine when I removed the Leupold bases. I bought the gun with the bases mounted - I dont use them. The screws were not tight but were all cross threaded going in! I'd lucky - I was able to clean up all the existing holes in the receiver with a tap afterwards.
The two front screw holes of the front base have the very tips of the Leupold screws in them, no sense fixing from there- too costly, but I did clean the holes out and made two new shorter screws - the correct length for these holes, for the new Talley Pictanny Rail. That's what I use and it wont be removed in future. I only had to Easyout one screw.....where the screw head broke taking one screw out ... the importance of not cross threading FFS.
This can be costly, people not careful when mounting bases onto xbolts usually cross thread screws. Brownells is the easiest and most cost effective fix. Or, dont get an xbolt! I only got this for a good deal - at the time. I have way better rifles!
I was lucky to fix mine and cost effective. Heres a few pics of my torment. I was lucky to make a save here.......