Figured you'd be somewhat interested CM!
"Murgatroid" ! Lol!! Been a while since i heard that!!
Well, they weld up the exterior screw hole opening, drill down the frame to the screw hole (both sides of the frame of course), thread the new holes for set screws, then open up the newly threaded holes on the inside (slot it to the inside) so now pins (a la Ruger') can be dropped in and held in place with the set screws.
The hammer is installed the same way (from the back) but nobody has been able to tell me how a hand can be installed when the hammer has to be installed from the rear!! Anyway, that's how they do that and yes its "just fer lookin" but the Colt factory did some 200+ of the "screwless" frames (3rd gens and 2nd gen open tops only, it's a "new" technique).
Abilene, take a peek. It's a little bit of "wow factor " but , you think that a "big deal" to leave out of an article is . . . kinda odd . . . whatever . . . Lol!!
Mike