22lr, I'm surprised. Usually those little derringers are either 25 rimfire or 32 rimfire.
They're actually nice little derringers. Quite well made, considering the price they sold for new.
Back in the day, I can remember seeing dozens of them at US gun shows for $10 each or best offer.
One fellow used to have a table at a half dozen shows with a cardboard box about a foot square, filled to the top with them, in everything from fair to exc condition, without any finish, nickel or blue.
They were never intended to be shot extensively and would soon become very sloppy.