Please note this magazine ban has no provision for grandfathering. You would be required to destroy or turn in standard capacity magazines or face felony charges. From the NRA:
On March 23, the Connecticut Joint Committee on Judiciary held a public hearing on two bills of interest to law-abiding gun owners in Connecticut: Senate Bill 1094 and Senate Bill 1210.
Anti-gun bill, SB 1094 is a bill in search of a problem, despite the recent media attention given to “large capacity” magazines, no correlation exists between the size or arbitrary capacity of a detachable magazine and violent crime. Owners of “large capacity” magazines are not criminals or individuals intent on committing atrocious acts; they are sportsmen or firearm enthusiasts who own the magazines for a variety of lawful reasons, including sport, competition or self-defense.
SB 1094 would prohibit the possession of firearm magazines that accept more than ten rounds of ammunition. If passed and signed into law, any person in possession of any magazine greater than ten rounds, who has not already surrendered the magazine prior to enactment or within ninety days after enactment, will be guilty of a class D felony. See full bill below.
Self-defense bill, SB 1210 would create a presumption under Connecticut law that it is reasonable to believe that deadly physical force is necessary to defend oneself from a person who has unlawfully entered a dwelling.
The Joint Committee on Judiciary has until April 15 to take action on these bills, so in the meantime, please continue to contact members of the Joint Committee on Judiciary here and respectfully urge them to support SB 1210 and to oppose SB 1094 and any legislation that forces law-abiding citizens to surrender their property. See full bill below.
Source: NRA-ILA