I see, I guess they already got stripped a bit. When replacing the screw it went in fully but never came to the point where it stopped turning/was screwed in. I dropped in a dab of super glue around the screw to make sure it doesn't get loose. (So hopefully I won't get bored of this grip :D )...
I changed the pistol grip on my S&W M&P 15-22 (to a Magpul MOE-K) and when finished, surprise: a piece of plastic on the floor:
I couldn't see an obvious place in the gun where it had come from. It's about 0.63"/1.6cm long and plastic. Does anyone know where it's supposed to go?
The rear...