Oklahoma Air Pistol made in Italy

Seeking info about this piece. Left side marked MONDIAL Cal 4.5 m/m, cast in raised letters OKLAHOMA, other side "made in Italy". Made of die cast, barrel has smoothbore brass liner, finish is nickel with white plastic grips. Shoots .177 air rifle pellets. Action: barrel breaks down to cock and load. Shape is similar to long bbl 22 auto, LOA 12 1/4 inches. Condition 95% nickel with couple chips on grips. I guestimate 1950s vintage. Appreciate any info and if any collectible value. Thanks, Robert