M1918a2 Bar acting “funny “

[Hiller]

Had a 20 round mag dump runaway.  Hxp ammo.  So did a disassembly/inspection/reassembly. Rifle looked fine inside and out. Recoil spring had proper length and action was smooth and properly lubed. Chamber was clean.  Paid special attention to trigger assembly and gas system. Thinking either the sear wasn’t grabbing the slide or there was insufficient gas pressure to drive the slide back far enough for the sear to catch. 

So I tried dummy rounds and the action worked fine. 

Set the change lever to single shot.

Loaded 1 round in the 20 round mag and it fired and locked the bolt open.  Loaded 2 rounds and it fired both with one pull of the trigger then locked the bolt back.

Loaded 2 more in the 20 round mag and got the same results. Shot both rounds on one trigger pull then locked the bolt open.

switched to a 30 round mag.  Loaded 2 rounds.  Now it changed to one round fired per trigger pull.  Worked perfectly in single shot mode.  Loaded 10 rounds in the 30 round mag and single shot worked perfectly again.  Loaded 30 rounds and sent 3/4 round bursts until mag was empty and the rifle works great.  Kicking the brass out forwards 2-4 meters.

 

I’m glad the rifle works but can’t for the life of me figure how a twenty round mag could cause the rifle to dump the whole mag.  I tried two different 20 round mags and had the same problem with both.  Can’t see the mags dragging on anything to create excessive friction.  Unless the cartridges in the mag are sitting up to high and somehow rubbing the bottom of the bolt.  But I’m not buying that either.  I don’t know why the mag would cause runaways.  

I’m sure someone here that has experience with the bar can explain this to me hopefully.  Probably something real simple I’m overlooking.

 

 

        R/s, Hiller............