those most likely, as my sets, are cadium plated.Recently picked up an older Hinsdale socket set and it had a full range of square sockets.
You can use a 3/8” 12pt socket on the Fullman style ones. I have been doing it for decades…Those square head "bolts" in beam clamps and bridge clamps aren't exactly bolts, but rather cup point set screws. It's why the head across the flats is the same as the diameter.