So in a nutshell "Yes," As long as you don't alter the AR with such things as a telescoping stock, change the barrel/upper so the barrel can accept any type of supressor, or have a magazine with a date stamped after September, 1994 and/or stamped "For Law Enforcement Only."
Again, make sure local laws, such as in NYC, dont prohibit the gun. Otherwise you have a rifle, not an "Assault Rifle"