Noticed something rear sight assembly (S&W Model 15 and 28)

[wpeel]

Is it normal for the rear sight assembly tang to be raised up at its front?  My Model 15 shows the tang slightly raised, though you can't see daylight under it.  The front edge is not flush with the frame.  The Model 28, the front edge extends beyond what I "think" it should, and there is a distinct curvature to the tang.  It definitely isn't flush with the frame and you can see daylight under it.  You can push down on it and it feels like it is under spring tension.  It makes me feel that it really isn't the proper part.  I don't have a way to take a high-quality photo.  These are both older guns.
I am reluctant to tighten the screw securing the tang any further....

*****

wpeel.... if it is a postwar drop forged sight leaf----sounds like it is----the SIGHT LEAF (rear sight body), curvature provides upward tension when the tiny sight screw at the fromt is tight. s recoil loosens the sight leaf, it is important to periodically check the screw with proper FLAT GROUND screwdriver (filed my own). Hold down pressure on shallow-slot screw.

S&W elevation screw----allow 3-threads screw engagement in elevation nut as maximum safe elevation adjustment.
David Bradshaw

[needsmostuff]

If you raise the rear of the sight (adjustment screw) as high as it will go, it will take the tension off the front screw (attachment screw).You should be able to then tighten the font attachment screw. Very small screw so don't get too frisky.
Then readjust the rear elevation adjustment screw.

[needsmostuff]

Oooops

[wpeel]

Thank you all. This site is a treasure trove of information.

[bradshaw]

wpeel.... when checking the S&W sight screw, I apply thumb pressure to the front of the leaf. The sight screw is small, with very fine thread; pushing the front of the leaf down, takes tension off the screw while turning it.

Jargon
* Leaf----rear sight base; until recent years, machined from a drop forging. Since it acts like one, may take its name from leaf spring.

* Slide----rear sight notch.
David Bradshaw