You can build a legal AR15. There is no such thing as "pre-ban" any more (those firearms needed to be registered in 2014 or converted or lost in the ocean)
Featureless is an option, it can be done with a thordsen stock and non-threaded barrel or with a Spur, fixed stock and non-threaded barrel.
Fixed magazine is another option, making the magazine non-detachable makes it not considered an "assault weapon" which means he can have all the normal features like a pistol grip, collapsible stock and threaded barrel.
What part of NY does he live in?
As for the Ares SCR, they function decently if you don't fuck with them at all. If you change anything on the standard configuration, they tend to not work so well. (despite advertising that they'll work with any mil-spec upper)