I think you're right bigted! They do have at least a certain amount of hardness. The big secret is, they don't have to be super hard to do what they need to do (but it wouldn't hurt either!). As long as the arbor fits and the wedge is in place under tension, there shouldn't be any damage to the wedge or the arbor or the barrel. It's when there isn't a good fit and no tension (or loss of tension from "thumb pressure") that damage happens. I know some CAS shooters use the " thumb pressure " thing but they shoot pretty light loads . . . and over time, they get sold and the person buying it sends it to me . . . then I get to deal with a beat up revolver ! I'm grateful that folks want me to fix them but honestly, new revolvers are much easier to set up /customize than worn out examples!!
As far as the op's question, I think Colt decided that a radius on the forward edge of the wedge would be prone to less wear while spreading the "load" area to the front of the wedge. The wedge spring is only there to allow the user to pull the wedge without removing it totally. The "new" springless wedge has a notch instead of a spring to serve as a keeper. Some wedges (I think possibly the fisrt examples) had a full length "notch" but (just as a problem with some of the sprung wedges) the wedge was probably prone to collapse as it proves to be weak. The notch then became much shorter to allow the wedge to remain solid for the most part. To me, this is the best wedge for all open top revolvers (of the Colt pattern). The flat on the wedge screw is just a convience for wedge removal without removing the screw totally (and loosing it!!).
When I setup a "captured" wedge, I'm essentially doing the same thing as making a "short notch" wedge. The spring is removed and re-mounted on the other end and then cut shorter. This arrangement allows the wedge to be installed and the spring (now shorter) pops up and locks behind the head of the wedge screw. The wedge is now "captured" and can't become loose! Removal is by turning the flat on the wedge screw to allow the spring to pass by.
Installing the wedge is the same as normal but before you tap the wedge, you turn the wedge screw tight again which pushes the spring down. Continue tapping for installation and you will see the spring pop up behind the screw head. That's how that works . . .
Mike
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