How to make your banned AR "Assault Weapon" into a non-banned semi-automatic rifle that does not need to be registered.
If you have a 1994 compliant AR it has at most three features that are currently banned. The (1)PISTOL GRIP, (2) FORE GRIP (3) THREADED MUZZLE with compensater or muzzle brake.
(1) Pistol Grip - Remove pistol grip (careful of detent spring), cut off about 2.75 inches of the grip. Re-install. Don;t want to cut your grip, new one's are 4.99 and up at Brownells.
(2) Fore grip - remove it.
(3) Threaded Barrel - Several options
1. Get a new upper or barrel that does not have threads. (Expensive)
2. Have a gunsmith remove the threads and re-crown the barrel if needed.
3. File off the threads yourself.
4. (Added later) Possibly permanently attach a threaded barrel cap.
If you want to register your rifle under NY SAFE Act it seems that you would be allowed to add the previously banned adjustable stock, bayonet mount, flash hider or grenade launcher
This from NY State http://www.governor.ny.gov/2013/gun-reforms-faq
Q: If I modify my gun by removing all design characteristics that makes it an assault weapon, do I have to register it?
A: No. If you modify your gun so that it is not an assault weapon, you do not have to register it. The modification must be permanent however. This includes, for example, removing the bayonet lug by cutting or grinding, grinding off the threads on the barrel, removing the foregrip so that it cannot be readily reattached, or any change that cannot be reversed through reasonable means.
Cut off pistol grip