9x19 in 7,63x25 chamber

[alvin]

Originally Posted by Morgan Kane

But the hammer does not release until the bolt is completely back into the forward position. First time hammer will fall by trigger pull, is not related to the bolts position on this broom look alike

It's supposed to be two-sear design then. The behavior matches Schnellfeuer perfectly. When the hammer is cocked by finger, it is locked by the 1st sear. Pull out the bolt, the trigger is not disconnected from the trigger in the full-auto mode (vs in semi-auto mode, the trigger is disconnected), so push the trigger will release the hammer, even if the bolt is open.

Please note, the hammer is locked by the 1st sear in the first time cocking. Why the 2nd sear does not get involved in this step? It's because the barrel extension is in full forward position, so the 2nd sear is in 'release' position. Keeping trigger pushed down, the 1st sear is effectively disabled, the 2nd sear controls the releasing of the hammer in the following firing, until the trigger is released to re-enable the 1st sear, or the gun runs out of the ammo, bolt is hold open wide by the magazine follower.

Regarding "fixing" the minor dimple on the barrel extension.... It's not broken, better leave it alone. "No change in my hands". Just IMO.