Before I bugger up something simple there seems to be some confusion on the exact size of allen wrench to use on the rear sight of a S&W Shield. I would imagine that it would be a proprietary size by Smith but can anyone definitively tell me the correct size please.
And if I understand correctly it will be best to perhaps use a soldering iron to heat the set screw to break the Loctite bond before trying to remove the screw.

Karl

OK since I did not get a definitive answer from forum members I called S&W and was told it is for sure a 1/16th. After locating a true by .062/1/16 wrench I will say yes it fits but a little looser than I would like to see it fit for such a small contact area. Perhaps I will warm the wrench a bit and hope for a little expansion.
Karl

***updated***
with correct allen wrench deeply seated into the setscrew the screw removed with no problem and without any heat needed. Though there was a tiny dab of a red thread medium on the screw it felt more like it was a sticky substance instead of a locking substance. Just be certain to firmly seat the allen wrench into the socket head before attempting to remove.