Hello All,

I just finised assembling the lower receiver for my M4 (semi auto).  All DPMS parts. DPMS lower parts kit, lower receiver and upper receiver.  I go to the range and insert a mag with three rounds.  I acquire my target, squeeze the trigger, and two rounds fire with one trigger pull (bang, bang).   I fired the third round and the bolt locks open as it should.  

I then load another mag with three rounds, repeat the above and again two shots with one trigger pull.  

What Gives??

Needless to say I was very upset by this, and I am anxious to get this corrected immediately.  Can anyone provide reasons as to why this happend and how this can be correct?  FYI, now modifications of any kind were made to any of the components.  

Thanks in advance for your help.

Srrch

If the hammer sear was "stoned" for a smoother trigger pull, that could do it

or a bad disconnector.
it happens...