S&W Adjustable Sight Question

[Animal Mother]

Over the weekend I bought a Model 17-3 S&W with adjustable sights. It is my first S&W revolver, and when I was sighting it in I noticed something that was unusual to me, but I'm sure there's a pretty simple explanation. When adjusting the rear sight leaf for elevation, I'd turn the screw at the top of the sight (the rear sight elevation nut), and the whole sight leaf assembly moves up or down. This is completely normal, but what I was curious about what prevents the rear sight leaf from bending or breaking when you adjust it up, since it is mounted in place by the rear sight leaf screw located towards the barrel. I suppose the rear sight elevation nut maxes out before it could damage the rear sight leaf, but I thought you guys might know.

 

[buttrap]

Its kind of a flat spring deal is all and made to felx.

 

[9mmepiphany]

Actually when you rise the rear sight, you are releasing the tension on the leaf spring, adjusting it down increases the tension on it

 

[dfariswheel]

Also, the under side of the elevation screw is a square nut that interlocks into a dovetail groove in the frame.
That provides a firm mount at the rear.

Here's an exploded view of a S&W revolver. The square nut is part 16.

http://www.stevespages.com/ipb-sandw-general.html