One of the reasons the all metal Ruger semi auto pistols were so over built was they were designed in the middle 80s when 10 mm was introduced and was growing in popilarity. Anyone who watched Miami Vice knew one of the detectives carried a 110 mm pistol by Dornaus and Dixon the Bren 10 as his main carry weapon. He carried a detonics 45 acp pistol in an ankle holster. Anyway the ruger pistols of the time were made to take 10mm. I have never seen or read about a factory made commercially released ruger 10 mm pistols . I do not know about prototypes etc but I mean factory production gun.