I have an '85 Detonics catalog/price list that shows a Colt OACP slide as an option on the Combat Master. Don't know if any were ever actually made that way, though. The key dimensions, I would think, are the relationship of the recoil spring tunnel and the stop surface in the frame. You'll probably have to use an OACP recoil spring guide and plug along with the slide. I use King's OACP recoil spring sets in my Combat Master, so the relative dimensions must be pretty close.