M&P Shield rear sight set screw damage

[dirt dobber]

Trying to replace the factory front and rear sights with tritium night sights. Front sight...no problem. Started on rear sight and found that no Hex wrench would fit the set screw. I know S&W says its 1/16", but its loose. I have tried metric 1.5mm (too loose) and 2.0mm (to big) and also tried SAE 5/64 (too big). I bought this gun new a few years ago and have never messed with the sights until now, so I don't know if the screw was rounded off during the new install process at the factory or what. Don't know what to do...anyone else ever experienced this problem or know what to do?

 

[GerSan69]

Not much help, but I have a bag of hex wrenches I've saved for years. All sorts of weird sizes, etc. Do you or someone you know have something similar? You might have one that fits laying around....

 

[chief38]

Small size Allen Wrenches often get rounded off and even though you might be using the correct size, the wrench will slip. Easy fix. Use a Bench Grinder, Belt Grinder, Angle Grinder, Dremel etc. and take off a small amount keeping the new surface flat. Remove burrs with a wire brush or wheel and you should be back in business. Don't over heat the metal because you do not want to loose the temper. This helps in many instances.

 

[Kp321]

My two shield rear sights take a 1.5 mm Allen wrench. A 1/16" is a little loose and could round out.

 

[chief38]

This is a method that is a bit out of the ordinary but I have made custom Allen Wrenches out of ones that were just a wee bit to large. All you need to do it bring dimensions down with a Belt Grinder or similar. If you have steady hands and a good eye, this should take less than a minute and works well. DO NOT over heat the tool. Works like a charm if you can't get to a hardware store that would carry one and you don't want to wait a week for an online order.

I have plenty of extra loose Allen Wrenches that always come with Scopes, tools, equipment etc. that I use as doaner's. My good sets stay unscathed.