I have a 590A1 with a speedfeed stock. The Hogue forend went on with no problems or modifications. The enhanced safety button from Brownells is another must have modification.
Try the Hogue forend instead fo the mossberg 590A1. Its cost about 20.00 and has a better feel to it. The blackhawk forend that comes with the nrs stock does not fit well.
Mossberg uses a one-way safety screw on their safeties. It is designed to be turned clockwise witha flat blade screwdriver. At the Mossberg armorer school, we are taught to use a small center punch to loosen the screw. Place the point of the center punch at an angle at the bottom of the slot...