This was my friday afternoon project. Been thinking about something like this for a while. Its a little clam shell that locks onto the factory lyman sight and lets you mount a red dot without making any permanent or even simi-permanent changes to the gun. Originally I was thinking to either unscrew the factory sight or drive out its big pivot pin. But I wanted to try avoiding removing the sight if I could. This clamshell idea is still in MK-1 alpha status. I really just wanted to check first how tight it would lock up before I sank too much time into it. Turns out it works really well. The next step is to refine it and make it less tall. I'm thinking that with a microdot with an aimpoint T1 style base or an RMR, it can get it tucked down much lower and sleeker. Then after that, try to knock it out in aluminum. Does anybody else have any red dot mounts they've done for the thompsons? I'd like to steal some ideas if any are floating around .