The state of New York has a number of different firearms restrictions on the books. Semi-auto rifles can only have a certain number and certain types of "features". The standard crop of Br4s have a threaded barrel to accept a muzzle device which NY says is a no no for the time being.
CMMG is looking into ways of bringing the Br4 lineup to New York as well as Illinois and Washington state which also have specific prohibitions that affect the Br4.