It looks to be poor QC. At the front of the magwell there are 2 protrusions. To the side of each one, on the side of the stock, there are cut lines. On one stock, those lines are even with the ends of the protrusions and on the one that I'm having issues with, they are forward. If those cut lines, which the magazine should rest on, are too far forward, then the magazine does not fully lock back on the tab on the trigger. This then allows the magazine to move forward and cause the Fail to feed and crushed rounds.