Since gunowner repression is typically incremental, I see the opportunity to shop for a stair step arsenal, so you always have the best legal weapons on hand.
Live legal M16 until they cancel your stamp.
AR15 until Ugly Features are banned.
Mini until detachable box magazines are banned.
SKS and Benelli until semi autos are banned.
Lever action and 870 until repeaters are banned.
And the last resort, a Biden Special double shotgun. Bear in mind that shotguns are always the last and least restricted firearm. You will still be prosecuted for using it in self defense, it has happened in England that I know of.
Join the Skeet club, that will give you a Socially Acceptable use for it.