S&W 5906 sight adjustment help, please.

[Primersinmyshoe]

I am used to BoMar type rear sights so this one has me stumped. A friend at the range asked me to adjust his rear sight on a S&W 5906. It is the rear sight that has the metal sides (with a cutout for the windage screw head). I tried to adjust the elevation screw but found it very hard to turn. Much harder that any other sight I have adjusted. So I gave up before I buggered it up.

Can anyone enlighten me on how this sight should be adjusted? I'm just a poor 1911 shooter who is not wise in the ways of the S&W autos.

Thanks.