K Model 18-3 Rear sight blade replace problem

[w8att]

I received my S&W kit for my Model 18-3 rear sight blade replacement & having assembly problems. I screw the windage screw into the blade (tried halfway, all the way, etc.) & put spring & plunger into windage screw head & push into Leaf (sight body) & compress plunger/spring with small needlenose pliers & insert into sight body fully but heres where I have a problem. Before putting on windage screw nut I try to turn windage screw & it will not turn with quite a bit of force. I've dissassembled & lubricated sight body & spring/plunger & still get same result when trying to turn windage screw after inserting into sight body. I tried even putting windage screw nut on till it just stopped to see if it was alignment problem but windage screw still would not turn. I don't want to hurt screw but can anyone tell me what I'm doing wrong?

 

[GunarSailors]

Does the blade slide all the way to the left, in and out, of the sight base without the screw? I hate ask that because you will have to pull it all out and remove the blade from the screw (another fine opportunity to lose the spring and plunger)... I had the same thing on mine and I think I might have stretched the spring when I was pulling it out, so I got a new spring and plunger and fixed the problem.

 

[w8att]

Rear blade install for Model 18-3 problem

Well I found the problem. Apparently I was sent the wrong rear sight blade kit as the pictures will show the windage screw is different from my original one. The detent hole in my original is closer to the center of the sight blade & its hole is deeper for the detent spring. I found this when I looked in my rear sight leaf (sight body) & saw a groove cut inside where the windage screw head is inserted for the detent plunger to ride in. After looking at my new windage screw I saw it would never match up because detent spring hole was more to center of screw head so I took out my saved broken windage screw head & found the difference. I hope this helps someone who has the same problem!

 

[GunarSailors]

Good catch! Maybe not the wrong sight blade screw, just bad QC?

 

[H Richard]

I think there is a difference in the vintage of the two different pieces. I would think it might fall within manufacturing tolerances. Does the new blade slide smoothly back and forth within the sight body? I had problems when replacing one of mine in a Pre 18. The new blade wouldn't slide in the slot in the sight body. I had to take a jewelers flat file and open the slot about .010". Even then it is snug.

 

[shawn mccarver]

Arguably, one of the parts most likely to fail under hard service is the adjustable rear sight. Unfortunately, S&W long ago discontinued earlier generations of the sight body, the various parts, etc. What the world needs now is an industrious after market company to make the various generations of sight bodies (for some reason, S&W moved the location of the attachment screw at least once) and internal parts, and now it seems the internals have had minute changes also... one wonders exactly WHO at S&W thought THAT was a good idea?

 

[w8att]

Thanks for all your replies. That's what I believed too that mine is an earlier design. I don't believe it was bad QC as the groove machined in the sight leaf lined up good with the old windage screw head spring detent hole plus the depth of the hole was quite a bit more deep (Almost twice as deep!). I'm going to try & get another sight leaf on ebay or somewhere so I can use the newer style windage screws.