US Patent 7841118 Training bolt for rifle

A training bolt for use in an automatic or semi-automatic firearm includes a training bolt installable in a bolt receiver of a firearm, wherein the training bolt is constructed and arranged with cutouts and protrusions which cooperate with the internal structure of the firearm bolt receiver and which allow function of the hammer/trigger/safety mechanism of the firearm, wherein the training bolt is configured to prevent, absolutely, chambering or firing a live round.