I have a Detonics Combatmaster that I need help identifying. It is serial
#I-56XX and has a Seattle stamp and Pat. Pend. on the slide. The hammer has a deep bow like the one in the parts drawing. It has a dual recoil spring. The grips and mainspring housing are pachmyr and the barrel is Colt MKIV series 70 NM. When I read the descriptions it looks like a MKV. What throws me off is that the finish doesn't look like the stainless I'm used to seeing. While it is bright metallic where there is slide wear, the exterior is matte and almost a champagne or taupe color. Is that a plating or a stainless treatment?
I would also like to find an original grip safety for it. It currently has an aftermarket beavertail. If photos will help I can easily email them to anyone.

Thank you for any information you can provide.

Jim