The semi-auto MG34 fires from a closed bolt, so when you let go of the cocking handle, the bolt should go foreward. Make yourself a little T-block of nylon 3" long to hold the bolt almost all the way open. The sequence is to pull the charging handle, insert your bolt hold-open, slowly release the c/h, lay in the belt, then pull a little furthur on the c/h. The T-block will fall out, then let go of the c/h. Ready to fire.
As to why your c/h falls out, the 'drop-in' cutout in the c/h slot is right above the rear handgrip rivet. In use, the c/h flange can never come back that far, as the rear of the c/h is stopped by the buffer housing. From the cutout, foreward, the c/h slot is continuous. Again, maybe your slot is too wide, or c/h worn down? No offense, surely you are putting it in correctly to begin with? Good luck...Phil
