I don’t think an 18 yo can own an “assault weapon” in CT. The registration law would have already gone into effect.
IANAL, though.
From the State of CT:
Assault Weapons
Section 53-202a of the Connecticut General Statutes gives the definition, and an itemized list of what weapons are considered Assault Weapons.
Definition. (1) Any selective-fire firearm capable of fully automatic, semiautomatic or burst fire at the option of the user or any of the following specified semiautomatic firearms: List of Assault Weapons
Who may possess Assault Weapons in Connecticut?
Law enforcement and military personnel may possess Assault Weapons in connection with their official duties, and any person who has a Certificate of Possession issued by the Special Licensing and Firearms Unit may possess the Assault Weapon listed on their certificate.
Can I get a Certificate of Possession for my Assault Weapon now?
No. The only exceptions to this would be a person who has been out of state serving in the military prior to October 1994, or a person who receives an Assault Weapon through bequeath or intestate succession providing the weapon already had a certificate. In these instances, the person has 90 days to register the weapon with the Special Licensing and Firearms Unit
I just moved into Connecticut and I possess an Assault Weapon. May I keep the weapon or if not what are my options?
Within 90 days of moving to Connecticut, you may sell the weapon to any licensed gun dealer, or you must do one of the following;
1) render the weapon permanently inoperable,
2) sell it to an out of state dealer,
3) relinquish the weapon to a law enforcement agency.
If you choose to keep the weapon you risk felony arrest.
I never registered my Assault Weapon, What are my options?
You can only render it permanently inoperable, or relinquish it to a law enforcement agency.
Can Connecticut gun dealers buy or sell Assault Weapons?
A licensed gun dealer may purchase any Assault Weapon that has a Certificate of Possession, or any Assault weapon that has been transferred into Connecticut as part of someone’s personal belongings for less than 90 days. The dealer may then sell them to other dealers, law enforcement agencies, or out of state.
Can Police Officers buy Assault Weapons?
No. Police Departments can buy them and give them to their officers to use, although the individual officers cannot buy Assault Weapons.
http://www.ct.gov/dps/lib/dps/special_licensing_and_firearms/assault_weapons.pdf
So if this is (and by all appearances, it was) a post-ban Bushmaster, it’s legal per CT law as it does not have selectable fire. Semi-auto only.
Those are not "assault weapons" by definition, if CT used the descriptive definition as the feds. Bushmaster, nor, XM-15E2 (what Bushmaster calls their AR's) are not listed by name in CT.
I think he needs a lawyer, one able to argue in federal court.
An HTML link...
CHAPTER 943
OFFENSES AGAINST PUBLIC PEACE AND SAFETY
Sec. 53-202a. Assault weapons: Definition. (a) As used in this section and sections 53-202b to 53-202k, inclusive...