Originally Posted by
DMCutter
I mounted my 509t on my new MR920 yesterday. I had to grind a fraction of an inch off the heads of the cover plate screws to get them below the Holosun mounting plate (0.08" according to Richie at Shadow Systems, but I didn't measure it, just went trial and error). Unfortunately it sits higher than an RMR or 507 so I'm going to have to replace the stock sights with suppressor height. Otherwise there was no drama involved with the mounting and the dot was dead on at 20 yards out of the box.