Trigger mechanism for firearms with self-loading actions

Abstract

The trigger mechanism allows the firearm to operate in a closed-bolt mode during semi-automatic fire and in an open-bolt mode during automatic fire. The mode change occurs only after the first round is discharged after the selector has been moved instead of when the selector switch is moved, thus avoiding undesirable mechanism noise or motion at the time of selecting the firing mode.

1 . A trigger mechanism for a firearm capable of both an open-bolt automatic mode of operation where a carrier spring-biased towards a forward firing position is normally held back from said forward firing position in a rearward position, and a closed-bolt semi-automatic mode of operation where the carrier is normally released into said forward firing position, said trigger mechanism comprising a selector operable to switch between said modes, said mechanism retaining an open-bolt configuration on being switched via said selector from open-bolt semi-automatic mode to closed-bolt mode automatic mode, and retaining a closed-bolt configuration on being switched via said selector from closed-bolt semi-automatic mode to open-bolt automatic mode, until a first round is fired after being so switched.  
   
   
       2 . A trigger mechanism as in  claim 1 , further comprising a carrier sear biased to engage said carrier to hold said carrier in said rearward position in said open-bolt automatic mode, said trigger mechanism including an auto-disconnect operable via said selector, said auto-disconnect positioned to block said carrier sear from moving into engagement with said carrier when in closed-bolt semi-automatic mode, thereby allowing said carrier to move to said forward firing position, and positioned away from said carrier sear when in open-bolt automatic mode, thereby allowing said carrier sear to engage said carrier.  
   
   
       3 . A trigger mechanism as in  claim 2 , having a trigger which when pulled contacts a surface of said carrier sear to move said carrier sear out of engagement with said carrier.  
   
   
       4 . A trigger mechanism as in  claim 3 , further comprising a disconnect spring-biased from said trigger to engage a hammer after firing of the firearm in said semi-automatic mode when said hammer is cocked by contact from rearward motion of said carrier, said trigger having a sear portion to engage a trigger sear on said hammer when said trigger is released, said disconnect then releasing said hammer; said selector blocking said disconnect from moving to engage said hammer when in said automatic mode.  
   
   
       5 . A trigger mechanism as in  claim 1 , further comprising an auto-sear, biased to engage a hammer to prevent said hammer from rotating to impact a firing pin, said auto-sear having a portion thereof positioned to be contacted by said carrier as said carrier arrives at said forward firing position, such contact moving said auto-sear out of engagement with said hammer, thereby permitting said hammer to rotate to impact said firing pin unless otherwise restrained, for example by a trigger sear.  
   
   
       6 . A trigger mechanism as in  claim 2 , further comprising an auto-sear, biased to engage a hammer to prevent said hammer from rotating to impact a firing pin, said auto-sear having a portion thereof positioned to be contacted by said carrier as said carrier arrives at said forward firing position, such contact moving said auto-sear out of engagement with said hammer, thereby permitting said hammer to rotate to impact said firing pin unless otherwise restrained, for example by a trigger sear.  
   
   
       7 . A trigger mechanism as in  claim 3 , further comprising an auto-sear, biased to engage a hammer to prevent said hammer from rotating to impact a firing pin, said auto-sear having a portion thereof positioned to be contacted by said carrier as said carrier arrives at said forward firing position, such contact moving said auto-sear out of engagement with said hammer, thereby permitting said hammer to rotate to impact said firing pin unless otherwise restrained, for example by a trigger sear.  
   
   
       8 . A trigger mechanism as in  claim 4 , further comprising an auto-sear, biased to engage said hammer to prevent said hammer from rotating to impact a firing pin, said auto-sear having a portion thereof positioned to be contacted by said carrier as said carrier arrives at said forward firing position, such contact moving said auto-sear out of engagement with said hammer, thereby permitting said hammer to rotate to impact said firing pin unless otherwise restrained, for example by a trigger sear.