I qualified at my PD today and used a parts washer they recently acquired to clean the AR. I pretty much soaked the rear sight before I realized what was happening and got rid of any oil the upper receiver ever had on it. Should I lube the rear sight and if so, how? Where exactly should I put a drop or 2 of CLP?
If the rear sight assembly has been totally degreased I would hose it with CLP and blow out the excess with compressed air or allow it to drain the excess out overnight while laying on a cloth.
To do it run the rear sight up fully.Then spray the assembly.Wipe or q-tip off any excess CLP you can after running it up and down in the upper a few times.
Remove the bolt carrier assembly and turn the upper upside down so you can see inside.You will see the hole for the rear sight assembly and the small detent hole in front of that.Apply a drop or two at the opening of each hole and allow to sit and penetrate for a few.Then run the sight up and down a few times allowing the CLP to penetrate into the holes.Particularly the small detent hole.As the knob moves the detent will cause a suction allowing the CLP to penetrate into the area of the spring and detent.
Flip the upper over and take a look at the windage knob.You will see a small hole there also.Place a drop of clp on/in the hole and work the knob back and forth...taking note of you setting of course.This will allow the CLP to penetrate and leave a film on that detent there as well.
Remove excess CLP as best you can leaving just a very thin film.Again compressed air helps force the CLP in and out leaving a thin film.You can buy a can of compressed air for computers at just about any computer related section and it works fine.
This all may sound a bit anal,but the rear sight assembly is steel as well as the detent and spring and they will rust making things a bit crunchy.Not a good thing.Plus a little lube helps the elevation adjustment barrel move easier.