I had to open up the dovetail in the rail using a file.
The light is rock solid.
Notice that the light is a bit lower than it should be. This is due to the thickness of the mount. The paddles that operate the light should straddle the trigger guard rather than be at the lower edge.
I doubt anything will fit. The Tac light I have is very small.
The adapter is very larbe. About the same size as the light 8O
I think there could have been a better design. I've seen an adapter for both a Walther and H&K that are near flush with the dust cover.