[tinydata]

My M1A rear sight (GI parts, SAI receiver) is having issues. Essentially, I cannot find a tension setting at which the elevation and windage adjustments are both properly set. If I leave the windage knob screw loose enough to adjust windage by hand, the elevation knob (its own screw snugged down tight) doesn't hold the aperture securely. If I tighten the windage knob screw another notch, I can no longer adjust windage but the elevation setting stays put.

Do I need new parts or am I missing something here?

 

[Ted Brown]

Check the tooth on the elevation knob. If it's worn it won't hold. Also check the tightness of the screw in the elevation pinion. If loose the elevation won't hold. It's also possible, but not probable that the detents for elevation on the receiver are not sharp enough and allowing the tooth to slip. Being a GI sight I'd suspect tooth wear first.

 

[Orlando]

The elevation knob tooth should be a sharp point, not worn over to properly hold

 

[sac troop]

There have been a lot of sights over the years that came from SAI that were not assembled with 100% G.I. parts.
I had one that came with my 90's Scout that the pinion was assembled with some non-standard parts. Instead of the dog washer and spring it had an internal retaining ring and rubber o-ring. Clearances for either of the parts were far out of speck. No way to properly adjust tension on the sight.
I swapped the pinion out for a G.I. correct one I already had. I have the tools to disassemble and re-assemble the pinions, (thank you Ted!), and eventually rebuilt the pinion with the correct parts and it works fine.

You might want to post some pictures of your sight to better address your problem.

 

[Instructor]

Not convenient, but if the small slotted screw head in the wind drum is tightened so much that the elevation drum is difficult to rotate, while holding rifle as normal, press inward on the elevation drum and that relieves pressure enough that you can rotate the wind drum.
Assuming you are right handed use left thumb to press and right hand to rotate wind drum. Tightened mine years ago for matches so as to not have the rack/aperture drift out of location, but after the match relieved the pressure in order to not overstress the spring.
Just a suggestion.

 

[smoothy8500]

I had the same issue with my Loaded model. Too loose, and one more "click" was too tight. I disassembled the entire sight and cleaned it well with mineral spirits and gave it a good blast with compressed air. It seems a little spec of grit somewhere in the windage knob was giving me the problems. Hopefully that resolves it for you.

 

[mb3]

I had a similar problem with a set of [email protected] sights on my M14s. I took them apart, cleaned them and re installed. So far so good.

 

[mic52]

Check the tooth on the elevation knob. If it's worn it won't hold. Also check the tightness of the screw in the elevation pinion. If loose the elevation won't hold. It's also possible, but not probable that the detents for elevation on the receiver are not sharp enough and allowing the tooth to slip. Being a GI sight I'd suspect tooth wear first.

This like Ted states was the problem with mine and not because I was smart enough to know for sure the possible cause vs. the way it looked and was lucky enough to have a NOS replacement part I bought here out the PX.

 

[Ted Brown]

That's great! It's always nice to be right once in awhile... Glad you got it fixed.

 

[TheShooter]

Here's a how a good USGI rear sight should work
[ame]https://www.youtube.com/watch?v=ovrAzjrqPDs[/ame]