Copy pasta from another thread:
The People's Republic of NY gun laws are new to me as well. Here's the quick version as I understand it. A semiautomatic rifle that accepts detachable magazines and has one or more 'evil' features (collapsible stock, thumbhole stock, pistol grip, threaded barrel, muzzle device, bayonet lug) is deemed an 'assault weapon'. These are legal only if owned prior to the unSAFE Act's passage and registered with NYS.
So you have a few options to avoid this.
1. fixed mag; now you can have all the features
2. featureless rifle; now you can have detachable mags
3. disable the semiautomatic feature; now you can have all features and detachable mags. But you've also turned your AR into a bolt gun.
If you want something that looks like a traditional AR-15, then you want to go with option #1. But if you must have detachable mags, then go with option #2 and get used to the ugliness.
Now that I've got a fixed mag AR, I must concede not being able to drop the mag is a bit of an inconvenience, even apart from reloading or malfunction clearing. Normally when I want to do a little maintenance on an AR, I'd insert a vise block in the mag well; can't do that with a fixed mag. Or if I want to show someone how an AR functions and operate the bolt, can't do that without chambering a round (or emptying the mag).
No matter which way you go, you are limited to restricted capacity (10rd) mags. Standard capacity mags (30rd) are illegal here; anything above 10rds is banned. Can't even have .22lr mags greater than 10rds. It is beyond ridiculous.