Any shotgun, semiautomatic or pump, that was legally manufactured prior to September 13, 1994 is not subject to Connecticut's Assault Weapons Ban (AWB) provided it is not "banned by name".
Pump shotguns manufactured after September 13, 1994 are not subject to the Connecticut AWB.
Semiautomatic shotguns manufactured after September 13, 1994 ("post ban) are subject to the Connecticut AWB. And as such are banned if they have at least two of the following features:
A folding or telescoping stock
A pistol grip that protrudes conspicuously beneath the action of the weapon
A fixed magazine capacity in excess of five rounds
An ability to accept a detachable magazine
Connecticut General Statute Sec. 53-202m.
Connecticut General Statute Sec. 53-202a.