[Solved]Cant lock up rear sight on a M.41.

[Dennis_dk]

Hi S&W forum.
I have a small problem.
The rear sight on my model 41 is loose.
Its the small lock screw thats loose.
And I bought the smallest allan wrench I could find in my local hardware store. Both in inc and mm. 1/16 and 1,5mm and they are to big.
So whats the right size?
And should I use blue loctite?

Thansk in advance.
Dennis

 

[Dennis_dk]

Solved. 1.27mm

I went to a tool shop, and got a 1.00mm and a 1.27mm.
The 1.27 mm fits.
Im guessing that the closest in Inch is 3/64.