I understand the adjustable sights are aluminum as well as the grip frame.
Howdy
Here is my old 45 Colt/45 ACP Blackhawk that I bought brand-spanky new for $125 in 1975. This was shortly after Ruger changed over to transfer bars in 1973.
I just took a magnet to it, and sure enough, the body of the rear sight is non-magnetic. So it must be aluminum. The rear sight blade is steel. They tend to be brittle and break easily, that is why Ruger raised the 'ears' on the frame to protect the rear sight blade from breaking. Sorry for the scratches on the aluminum, I have had this revolver for a very long time.
Here is a shot of the Micro rear sight on a Three Screw 357 Magnum Blackhawk from 1962. This one ids built on the medium sized frame. Notice this frame also has the raised ears to protect the rear sight. Sorry, I did not dig it out to see whether or not the body of the sight is magnetic.
Here is the Micro rear sight on a Three Screw 44 Magnum Flat Top from 1956. No raised ears to protect the rear sight.
Another view of the Flat Top 44 Mag rear sight.
Still another view. Notice the 'plum' color of the loading gate. Ruger was having problems with the blue on their Investment Castings back then, they would sometimes turn purple. It turned out they had too much silicon in the steel alloy. Shortly after this, the alloy was changed slightly and the plum colored castings went away.
A shot of the Three Screw Flat Top 44 Mag.
Regarding getting used to the 'Colt style' of setting the hammer to half cock to load: As I said I bought my old Blackhawk with the transfer bar in 1975. It was the only single action revolver I owned for many years. So needless to say I was used to simply opening the loading gate to load six then closing the loading gate. I did not buy my first colt style single action revolver until about 2000 when I started shooting Cowboy Action. It took about an hour or so of playing around with the gun late at night, shooting bad guys on the TV to get used to loading a single action by setting the hammer at half cock and loading one, skipping one, loading four more, bringing the hammer to full cock and lowering it on an empty chamber. Been doing it for almost twenty years now and it is second nature. Now loading a Ruger seems strange. Which is part of the reason why, by the way, that I installed after market half cock hammers in three 'original model' Vaqueros. Now they load just like my Colts.