I recently received my RRA 9mm upper. I am using a Hahn bottom loading magazine block. The lower is a M-16A2 sans auto sear and full-auto selector (work lower). Magazines are new Colts.
I've had two range trips and the gun would not run on either. Initially, I was using Winchester 124 grain white box. Today, I brought along some Winchester 115 gr white box and some NATO spec rounds as well.
From my intial impressions I thought the gun might be short stroking so I though the hotter ammo would solve the problem. I also pulled the bolt, wiped, and lubed it and cleaned the powder debris from the upper. None of this helped.
The gun has two major problems. The first only showed up today. Using a mag well hold, the Hahn would become loose and apparently cause double feed problems. The Hahn was slowly slipping out to the degree that the magazine release had significant tension on it. Not using a mag well hold seemed to solve this problem.
The major problem is a failure to eject. It is impossible to fire more that 8-10 rounds without the gun malfunctioning. Typically, the spent case is pointing straight out the ejection port with the fresh round jammed underneath it. Other times, the spent round is pointed up at roughly a 45 degree angle and tied up with the fresh case. These tend to really tie up the gun to the point that you cannot cycle the charging handle. Clearance requires tapping the buttstock on the ground while pulling the charging handle to the rear. As an odd note, roughly 85% of the time, the last round fired stays in the action after the bolt locks open. I've also had some odd instances of a fired case making it past the ejector and ending up in the firing group which is an interesting clearance procedure.
Throughout the range trip, I cleaned and lubed the gun. The best it ever ran was 15 rounds of Nato ammunition immediately after a good cleaning but that was the only time that so many rounds were fired without problems.
I have been able to simulate most of the ejection problems by running the charging handle slowly. The bullet spins in the action and goes nowhere. If I run the charging handle hard, the rounds eject as they should.
As a final note, the lower I am using is NOT the lower the upper will ultimately be used on. I plan on having the bolt ramped and installing a neutered M-16 hammer in my personal gun.
Any suggestions on fixing this problem? Should I wait 'til the bolt is ramped and I'm using the upper on the intended gun to solve the problems.