In case you hadn't noticed more and more states are outlawing "assault weapons" and "high capacity magazines" almost weekly now..
I do not know if your assertion is correct, and you provide no data or cites to prove your assertion. Perhaps in New York and other progressive bastions, but IIRC +/-27 states have veto proof majorities that are Republican controlled. I would not believe that those states were banning MSR's, (Modern Sporting Rifles).