Rooikat21

Can anybody enlighten me as to the difference between a pre and post-ban M1 tactical with pistol grips and ghost rings? I was looking to get one sometime soon and to my surprise saw some being advertised a pre- and post-ban weapons. I didn't know there was any legislation affecting shotguns. If someone could let me know so I could make a pruchase decision, I'll be buying used anyway, I'd love to have an M1. Thanks!