During my brief searches, I didn't find much regarding direct mounting an M600 on the Geissele SMR, so I thought I'd provide some additional info. I saw a post from what I believed to be an Airsoft gun on another form and attempted to do the same using two 8-32 1/2 flat head machine screws and two (#10 I think) washers. I also bought two 8-32 3/4 screws, which would have made mounting far easier, however, they were too large to fit under the handguard without snagging on the gas block.
Getting the light exactly where you want it is rather tricky, but I'd recommend putting the screw towards the end of the barrel in first, tightening it about halfway, then sliding the second mounting hole in line with a rail hole, tightening it down halfway before finally adjusting the light to its final position and fully tightening everything down. Took approximately 30 minutes of messing around to figure out, but once you get the hang of it you should be able to remove and remount it fairly quickly.
TLDR; The M600 mount uses 8-32 threads, screw the light on from the inside of the handguard using washers to prevent the screws from slipping through the holes in the rail.
![Trigger Air gun Gun barrel Gun accessory Cylinder]()
Getting the light exactly where you want it is rather tricky, but I'd recommend putting the screw towards the end of the barrel in first, tightening it about halfway, then sliding the second mounting hole in line with a rail hole, tightening it down halfway before finally adjusting the light to its final position and fully tightening everything down. Took approximately 30 minutes of messing around to figure out, but once you get the hang of it you should be able to remove and remount it fairly quickly.
TLDR; The M600 mount uses 8-32 threads, screw the light on from the inside of the handguard using washers to prevent the screws from slipping through the holes in the rail.
