The bolt and bolt carrier shown in Saturdays post.
Comes from an 8×57 Dror machine gun. Here are a few picture of this weapon.
One of the unique items about this LMG is the open bolt operation while on full auto and the closed bolt operation while on semi- auto.
Here is a close up look of this fire control system.





“One of the unique items about this LMG is the open bolt operation while on full auto and the closed bolt operation while on semi- auto.”
http://en.wikipedia.org/wiki/FG_42
“The FG 42 fired in semi-automatic mode from a closed bolt, accomplished by delaying the release of the firing pin (mounted on the bolt carrier and released by the front sear notch) until after the trigger had been pressed; the short lock time, and little movement in the action during firing translated into greater single-shot accuracy. When operating in the automatic mode, the sear mechanism was designed to fire from an open bolt by simultaneously releasing both the bolt and bolt carrier. This had the advantage of preventing a phenomenon known as “cook off” where the heat of repeated rounds being fired caused a chambered round to overheat and prematurely ignite the powder or primer. With automatic fire selected, the bolt would remain open between bursts to provide maximum cooling. The rotating fire selector switch was situated in the trigger group, above the pistol grip on the right side. The change lever also served as the safety,[10] disabling the sear mechanism when engaged.”
Yes but the Dror seems to be hammer fired. FG42 has similar bolt to Lewis-gun. There is no hammer on it.