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The Dardick tround, or simply tround (triangular round), is a unique firearms cartridge developed by inventor David Dardick for use in his open-chamber firearms. Named for its convex triangular shape, the tround allowed the firearm's chamber to be open on one side, removing the requirement for reciprocating motion when chambering and ejecting a cartridge.
It was used in several revolvers: the 10-tround Dardick Model 1100, the 11 or 15-tround Model 1500—and the 20-tround Model 2000.