ok, so, i have a TM p226 which ALEGEDLY has a 20mm mount. however, i also have a king arms laser and mount which is also 20mm, and the mount clamps the pistol frame closed and the slide jams on the way forwards.
i also have the same problem with my glock 23.

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now, am i tightening it too much? are there any other cases of this happening and whats my best course of action to remedy the situation?
ive tried using a dremmel to widen the mount, but again when tight enough to not fall off the mount clamps the frame close