Mounts? yes and no.
Dunno if they were MEANT to be mounts but I mounted stuff this way:
slide thin strip of brass (Ace hardware. like $3 for the piece). IIRc its .040 thick and just about 20mm wide, although I did have to sand one side a bit to get it to width-wise. You dont NEED the brass(could be steel) but itll stop the screws from buggering up the bottom of that channel when you tighten the screws
Had this bit of rail in the “parts box” (think its a Ruger rail of some sort)
I used a couple of “T” nuts with the edges milled down and where the bolt gets screwed into so the rail would tighten against the frame.
Couple things to mention: first, you have to be VERY careful to remove the same amount on either side of the T-nut. Otherwise it’ll center itself OFF-center and your device will be pointed up or down a bit. The base of the nuts will JUST barely fit with the brass shim in place. You may have to mill/grind/file the “height” of the T-nut to let the rail sit down low enough. ANd you may have to shorten the screws so they tighten all the way down but dont bottom out too soon. Some experimentation was needed to get those sized correctly
Slide the brass shim in, then the rail/nut assembly and tighten the screws down. If youve got everything setup correctly, itll snug up and be very tight.
Dont have a pic with it all assembled. really surprised I still had these pics in my phot album on the iPad.
So I cant say those areas of the gun were meant to be mounts, but you can use them to mount lasers or flashlights this way.
