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Do you know if that required additional machining, or a lucky coincidence that the dovetails match? Is there still a little half-a-hole where the Coltmaster windage screw was located?
I don't think the later accro sight used a traditional dovetail. Rather there was a groove in the topstrap and the sight rested in there, held in by a pin, with a screw and a spring which adjusted for elevation. In addition, the rear corner of the top strap on the latter OMM was removed, so the bottom of the sight could rest below the top strap level. The maching was totally different on a OMS, with what looks to be a traditional dovetail, although I don't have a OMS in my collection. I'm not sure how you could swap the two different sights without much grief.
Here is an OMM rear sight, the "accro" type