Just got one of theTANDEMKROSS Shadow Mount V3.0 for Ruger Mk pistols and it seems well made(everything lines up, machining, and finish are nice.
https://shopruger.com/Mark-IV-Mark-III-22_45-Picatinny-Rail/productinfo/90623/
The written and video instructions here:
suck, at least for the RMR footprint since it uses 2 set screws in lieu of studs for the front holes.
Other than advising which fasteners to use, there are no details on how to install and the video fast forwards thru this step.
The holes for the set screws are drilled/tapped all the way through. I assume the dude knows how far to screw them in(but doesn’t share that info), but instructions related to their V2.0 mount advise installing the set screws from the bottom.
So instead of following their instructions, prior to installing the mount on the receiver install the RMR footprint dot first.
- put the dot on with the 2 rear screws snug
- apply loctite then install the 2 set screws from the bottom until snug
- remove the 2 rear screws and the dot
- install the mount using loctite on the screws
- place the dot on the 2 set screws
- loctite the rear screws for the dot and snug down