I have Model 116FSAK in 300 RUM large shank with a flat back receiver I will swap the barrel for a 338 Edge one, now the problem the rear of the action (flat back) have a slight slope towards the rear (about 0.10" to 0.15"), when I put a Ken Farrell long action flat back scope base the base touch only the front of the rear flat (first screw hole) but make full contact with the front round part of the receiver, is it a common problem with flat back receiver? I know bedding the rear portion of the base will probably fix this problem.

I tried a Leupold base with the same result.