i have a ssk tsob on my 14" ss 44mag. i used 3 burris zee rings, and they went on fine. the tsob was a short version with only 2 slots, so i had it milled for a 3rd slot. good deal
maybe your rings are squeezed in a bit, after tightening down on a smaller base? :? can they be opened up a tad?.......or?
virgin valley custom guns(vvcg) makes an all steel weaver type base that also accepts weaver type rings. i have one on my 15" .243 encore, and use 3 burris signature rings on it.