here you go from wikipedia
Assault weapons ban in New York politics
New York's version of the law is very similar to the Federal version, but New York's version does not have a sunset provision. According to the laws of the State of New York, a magazine with a capacity of more than 10 rounds manufactured after September 14, 1994 cannot be legally possessed by anyone other than a law enforcement officer. A provision of the Federal law required the date of manufacture to be stamped on every newly manufactured "large capacity" magazine. Because that requirement is no longer in effect, the New York magazine ban becomes potentially unenforceable except with respect to those magazines manufactured during the ban and marked according to federal regulations then in effect.
NYS Penal Law § 265.02(6) makes it a class D felony to possess "a large capacity ammunition feeding device," which is defined in Penal Law § 265.00(23) as "a magazine, belt, drum, feed strip, or similar device, manufactured after [September 13, 1994], that has a capacity of, or that can be readily restored or converted to accept, more than ten rounds of ammunition." Possession of unmarked "large capacity" magazines made after the sunset of the federal ban thus subject New Yorkers to felony charges. Police and prosecutors may be able to determine actual manufacture dates of seized magazines from information not generally available to consumers, such as the dates of magazine design changes and parts assembly numbers. The New York ban thus leaves possessors of unmarked post-ban magazines at risk of felony charges since they may not know the magazines were manufactured post-sunset and not pre-ban.
During the period of the federal ban, ATF would issue rulings as to whether attachment of a given muzzle device on a post-ban rifle was permissible because it acted only as a brake, or impermissible because it acted as a flash suppressor. As with magazines, the New York regulatory scheme implicitly relied upon such federal regulatory determinations for enforcement of the state's ban. With the sunset of the federal ban, ATF is no longer concerned with classifying muzzle devices. New York residents now may acquire or modify rifles attaching what they believe to be muzzle brakes, but which at some point New York police or prosecutors may deem to be flash suppressors, resulting in arrest or prosecution for unwitting possession of a banned rifle. [See NYS Penal Law § 265.00(22) defining "Assault Weapon" to include "a semiautomatic rifle that has an ability to accept a detachable magazine and has at least two of the following characteristics... (iv) a flash suppressor or threaded barrel designed to accommodate a flash suppressor." There is no definition of "flash suppressor" in § 265.00, which contains all definitions for the ban, thus leaving grounds for arrest and prosecution uncertain until what is or is not a "flash suppressor" is resolved by state courts or clarified by statute.]
