US Patent 10386142 Reversible bolt for ambidextrous ejection

Provided is a firearm bolt having a rotating bolt body with a longitudinal axis with an extractor on the bolt body at a radial position relative to the axis. There are at least first and second transverse bores in the bolt body at an acute angle to one another converging at the longitudinal axis for selectively receiving a cam pin. Configuration of the bolt in a bolt carrier with a cam pin in the first transverse bore positions the extractor for interaction with an ejector to eject a cartridge casing to one side, and configuration with the cam pin in the second transverse bore positions the extractor for interaction with an ejector to eject a cartridge casing to an opposite side.