Last Friday, I ventured into the valley and bought a New Mossberg 590A1 Model 51668. Got it home and loaded one round in the magazine. Racked the slide and nothing...... Looked into the receiver and found the cartridge interrupter was retaining the round and not allowing it to stage onto the cartridge stop. I contacted Mossberg , Joseph Zakher (email@example.com) and they are shipping a new cartridge interrupter. This is apparently a known issue, but a big thumbs up to Mossberg for their customer service a big thumbs down to their QC.