They are made of steel, but stick with the Williams. If you don't like the 5D go with the Foolproof.
A few years ago my silhouette club started shooting Cowboy Rifle Silhouette. We all got our guns and most of us ordered Lyman Reciever sights ofr them. Some of them would not work from the very first, poor quality control. Mine worked for one season, the nest season, early, I was shooting a match and while I was shooting turkeys something flew off of my gun. I looked and the Vertical Admustment screw broke off and flew away. Lyman said it was out of warrenty. I didn't want a new one anyway.
Now, about 4 years later, no one in my club uses a Lyman Receiver sight. Some are using Marbel's Tang sights, Williams FP sights, and few lucky ones have found an old Redfield that they could afford. The Lymans are just a bad memory.
I have Williams FPs on my smallbore cowboy rifle and pistol cartridge cowboy rifle and really like them. They have positive click adjustments and are stable and repeatable. I have an old Redfield on my 30-30 cowboy rifle and it is the best receiver sight made. I found it on a used model 94 in a pawn shop and traded the rear sight from my model 94 for it. What a deal.
Sixgun