Tape and glue work great for some things however even keeping something as light at a front sight affixed with glue is prone to failure. Underslung like that you have all the recoil forces working against you.

I would feel alot better about that mount if it were more positively affixed. Maybe something similar to the Weaver no drill mount for the Super Blackhawks or a sort of inverse scope ring. Something that you could pretty much be assured is not going to come off.