last year i installed the #45MV. the other day i noticed something looked a little off about it... after a couple of minutes i realized that the top rail forward of the flattop (the part that can flip up) had a thumbscrew underneath it that was causing the rail to bow up very very very slightly (about 1mm)

does anyone know what this thumbscrew is used for? the head of the screw is about a 1/4" diameter and it has the same threads as the rail screws.

after looking it over, i decided that it served no purpose that i could see and removed it. the rail is perfectly straight now...

did you get the sir used?


i have never seen any thumbscrews anywhere on the sir's i owned.

nope i got it brand new...

I have the 45m also, and the thumb screw is there but i never had a problem with it like you described. I just always thought it was there to give that part of the rail just in front of the flat top alittle xtra support, so i left it in. It seemed like it was made fat and wide for that purpose.
Im not really sure, just a guess.