I bought one of the magnums as a backup in the late 1960's. I did manage to break a firing pin and replaced it without incident, maybe 10 years ago. You can fire .22lr in the magnum version, but accuracy suffers. IIRC, the lower barrel is off on windage.

Mine is a bit loose, but the looseness is between the sideplates and the pivot pin. Lockup of the breech is tight, the breech & barrels just wobble a mite.