US 7,578,227 B1
Fire control mechanism for selectable fire
Adam M. Jacob, Brodheadsville, Pa. (US)
Assigned to The United States of America as represented by the Secretary of the Army, Washington, D.C. (US)
Filed on Apr. 21, 2008, as Appl. No. 12/106,624.
Claims priority of provisional application 60/913302, filed on Apr. 23, 2007.
Int. Cl. F41A 5/00 (2006.01)
U.S. Cl. 89—141  [89/139; 89/140] 17 Claims
OG exemplary drawing
 
1. A fire control mechanism, comprising:
a first shaft;
a hammer rotatably mounted on the first shaft, the hammer including a detent formed thereon, the hammer being biased for rotation about the first shaft in a first direction;
a second shaft substantially parallel with the first shaft;
an auto sear mounted on the second shaft and engageable with the hammer detent, the auto sear being biased for rotation about the second shaft in a second direction that is opposite the first direction;
a semi disconnect mounted on the second shaft and engageable with the hammer detent, the semi disconnect being biased for rotation about the second shaft in the second direction, the semi disconnect being disposed further from the hammer detent than the auto sear;
a third shaft substantially parallel with the first and second shaft;
a primary sear mounted on the third shaft and engageable with the hammer detent, the primary sear being biased for rotation about the third shaft in the second direction, the primary sear being disposed further from the hammer detent than the semi disconnect sear;
a movable bolt that, when moving rearward, engages the hammer and rotates the hammer in the second direction such that the auto sear engages the hammer detent;
a bolt carrier engaged with a rear end of the movable bolt, the bolt carrier, when moving forward, engages the auto sear and rotates the auto sear in the first direction such that the auto sear disengages the hammer detent;
a protrusion disposed on a side of the semi disconnect, the primary sear being operable to engage the protrusion such that the semi disconnect rotates in the first direction and disengages the hammer, the primary sear engaging the protrusion as the primary sear rotates in the second direction, the primary sear engaging the protrusion before engaging the hammer.