Sub-caliber firearm

A sub-caliber automatic pistol of the double-action breech block type including a frame having barrel-mounting ribs, a handle, a barrel-receiving slide with integral breech block, and a firing mechanism of a pistol of a larger caliber and a magazine adapted for storing a plurality of sub-caliber cartridges, said sub-caliber automatic pistol comprising

• A. an interchangeable barrel, said barrel having a bore adapted for accommodating said sub-caliber cartridges and terminating rearwardly in a downwardly descending lug having an integral feed ramp defining a first cartridge feed line defining a cartridge path for cartridges of said larger caliber, said barrel being detachable, selectively movable with respect to said frame, and selectively locked in engagement with said slide by barrel ribs integral with said barrel and matable with said barrel-mounting ribs on said frame, said barrel ribs and said barrel-mounting ribs being substantially parallel to a central longitudinal axis of said barrel, said barrel ribs including at least one rib terminating at a first end proximate said feed ramp,
• B. Feed spacer means affixed to said barrel lug for defining a second, continuous feed line, said feed spacer means including an upper surface substantially intersecting with a surface of revolution defined by said bore, said second feed line defining a sub-caliber cartridge path which is elevated with respect to said first cartridge path, said second feed line having a selected vertical displacement from a horizontal plane defined by at least one of said barrel ribs,
• C. ejector means interconnected to said slide for striking and ejecting a spent sub-caliber cartridge, and
• D. extractor means, including a substantially rigid extractor element, for extracting sub-caliber cartridges from said magazine.