Black Aces Pro Series M Optics Rail?

[Pippu_Paladin]

To sum up 15 months worth of lore my brother went to buy a Remington 870 DM for home defense at the beginning of our current pulmonary kerfuffle but his LGS had sold him a gun they didn't have and with Remington going belly up he never got it.

I'm thinking of getting him a Black Aces Pro Series M Pump, but in anticipation of the DM I had bought him a red dot thinking I could just get him the side rail optic mount thing. I e-Mailed Black Aces and they alluded to such a mount for their shotguns but when I asked for further clarification I got no further responses. Does anyone here know if their receivers take similar hardware to Mossbergs, Remingtons, Winchesters or some other common shotgun or if it's a proprietary thing?

Any help would be greatly appreciated.