it is a trigger over travel stop, it is just a small screw that holds it in and has come loose, if you use it for target shooting no need to take it out, clean all dirt and oil from the area and just slightly tighten it down and adjust it to stop the rear-ward travel of the trigger to just as it releases the hammer.use some locktite and firmly tighten the screw down. you will now have a trigger that will not throw your shot off .
If used for protection just unscrew and remove it.
There are people looking for these cams and screw so you could offer it for sale here.