M1 Garand is still legal, first it's not a detachable magazine. Second there is a C&R clause in the AWB law. Anything 50 years or older is considered a curio or relic and doesn't fall under the ban. Go ahead and order your CMP, you'll be fine. By the way there's an exemption for the 7 round rule for shooting at an incorporated firing range or in competition recognized by the NRA. Check out
http://www.governor.ny.gov/2013/gun-reforms-faq for the FAQ on the new law.
Stu