I've had an M4 for 18 years. It is the shotgun equivalent of a Glock in terms of reliability. You need to ditch the stupid two-part mag tube and get a one piece mag tube immediately. The collapsible stock is nice for saving a little space, but my actual preference is for the non PG straight stock (I have all three). You can ghost load the M4, so 7 in the tube, one on the carrier, one in the chamber for 9 shots. With a full card on the side, its a heavy bitch, but its an end of the world shotgun...The 1301 Gen 2 is a damn good shotgun with the proven A400 operating system. If weight is a primary concern, that's the way I would go. The A300 is a noticeable step down in the operating system/refinement in my opinion.