Got a front sight post for a USP that got loose all the sudden.  Its a dovetail fit.

Was thinking loctite on the slot and then slip it in.

What else could fix this?  It was never loose before then all the sudden bam!

Is it all metal?  If so, the usual fix is to take a punch and peen some of the metal from the slide into the sight.

If you look carefully, you will see that the dovetail it tapered (its wider one side than the other).

The sight is intended to be inserted at the wide end, and moved to the correct position moving only towards the narrow end. If you try to move backwards it comes loose.

The only real answer is a new front sight insert, and to be very careful when aligning it, because you can't go backwards.

You can try glue, swearing, prayer and voodo, but you will end up buying a new front sight.