I believe this is the law...
Magazine capacity
Effective April 15, 2013, only magazines that contain seven rounds of ammunition or less can be sold in New York. Magazines that can hold more than seven rounds but not more than ten rounds and are currently possessed will be grandfathered, but may only be loaded with seven rounds. By January 15, 2014, magazines that have the capacity to hold more than ten rounds of ammunition that were grandfathered by 1994 legislation must be discarded or sold to a licensed dealer or an out-of-state purchaser. Exceptions are made for large capacity magazines that are curios or relics.
Exemptions to allow manufacturers, licensed dealers and police officers to possess large capacity magazines continue to apply, except for an apparent drafting error in the NY SAFE Act that can read to prohibit anyone from possessing a magazine that is loaded with more than seven rounds. The exemption provided by Penal Law §265.20(a)(8) for manufacturers of “large capacity ammunition feeding devices”, etc. was unchanged, so that Section 265.02(8), which makes possession of a “large capacity ammunition feeding device” a class D felony wouldn’t apply to a manufacturer, even though the definition of a “large capacity ammunition feeding devices” has been expanded. This would be the end of the discussion except that the SAFE Act added two new sections banning certain magazines that are not exempted by Section 265.20:
• Penal Law § 265.36: Makes it a class A misdemeanor to knowingly possess a “greater than ten” magazine manufactured before 9/13/1994, if owned before 1/15/2013.
• Penal Law § 265.37: Makes it a class A misdemeanor to knowingly possess an “ammunition feeding device” that was possessed before 1/15/2013 if it has a capacity of “more than seven but less than ten” if loaded with more than seven.