Win 94 - stripped rear sight screw hole

[bison]

Hi all - I just bought a late '40's Win 94 that came with a Lyman aperture sight installed. I took the whole thing apart to give it a good cleaning and noticed that one of the two screws that holds the Lyman sight to the receiver is stripped. What should I do?

Based on the castbullets website http://www.castbullet.com/misc/tdown.htm I presume it's an 8-40 screw that may be fixed by cleaning out with a tap. Is this the right thread and a good idea? Should I also replace the screw (or both of them) at the same time? Or is this a job for a gunsmith?

Thx!

 

[Jim Watson]

Caution, I am not a gunsmith. Until one shows up..

Is the screw or the hole in the gun stripped?
It is probably a 6-48 but you need to know for sure before doing anything to it.

If it is the screw, replace it.

If the hole, and if it is 6-48, Brownells makes an oversize No 6 tap and screw to salvage such situations. Or you could go to 8-40 but would probably have to alter either the screw head or counterbore.

If it is some odd size, Loctite Form-A-Thread might do well enough for one screw if the other is good.

 

[bison]

Great questions Jim so I did some investigating. The hole is definitely stripped and not the screw - I verified this both visually (the bad hole looks messy vs the good one) and by swapping the screws (both were fine in the good hole and bad in the bad one).

I believe it is indeed a 6-48. I measured the outside of the thread of the screw and got about 0.134" (I believe #6 is supposed to be 0.138" vs #8's 0.164"). I then counted the threads on the screw and saw 8 in about 0.165". 8 threads at 48 tpi would be 0.167 vs. 0.2" at 40 tpi. The screw is 0.25" long (length below the bottom of the head).

Based on these measurements being so close to theoretical, it must be a 6-48. So sounds like I should try the Brownell's oversize tap?? I was thinking about the loctite solution that you mentioned, though it's always an alternative if the Brownell's solution doesn't work...