Luger Artillery Pistol

[michael1@windstream.net]

My gun was doing the same thing. Upon investigation I found the the trigger lever was not pushing the plunger in on the sear back when it jacked in the next round. Instead it was over-riding the plunger and causing the sear to disengage just as the bolt cloesed up on the second round.
I removed the flat spring and sear bar. I then removed the pin from the sear bar that holds in the plunger and spring.
The inside of the plunger hole was clean but the spring was very stiff. Actually the spring was too stiff.
So instead of the trigger lever pushing the plunger in - it was riding over the top of it and disengaging the sear. The plunger is supposed to push in when the bolt returns to battery. When you release the trigger the plunger pops out and the gun can be fired again.
I chose a weaker spring of the same diameter and trimmed it to length. I made sure the plunger worked in and out easily. It doesn't have to have much pressure - just enough to push the plunger out when you release the trigger.
Put it back together and all is well.

Thought this migh put things into to perspective of how and what that little plunger does.

Mike