AFAIK you can posess and purchase mags larger than 10 rounds… they’ve been grandfathered in…
You can own guns that are pre-ban that have post ban stuff (Bayonet mounts, flash supressors etc) These things are only legal on pre-ban and must be welded to the gun (Can’t be detachable). Same thing is with the larger mags, can posess them and use them… just can’t be made after the bans
(Unless they’ve change the law recently)