There really aren't a lot of gun companies located in anti-gun States that I feel the desire to buy from, with exception of perhaps S&W.
Let's look at a small list (I'm sure I'm missing a couple)
With Headquarters or manufacturing facilities in anti-gun States:
S&W: Springfield, Massachusetts
Colt: Hartford, Connecticut
Charter Arms: Shelton, Connecticut
LMT: Milan, Illinois
Kimber: Yonkers, New York
Armalite: Geneseo, Illinois
Henry: Bayonne, New Jersey
Rock River: Colona, Illinois
Savage Arms: Westfield, MA
Seecamp: Milford, Connecticut
Kahr: Blauvelt, New York
Stag: New Britain, Connecticut
Springfield: Geneseo, Illinois
Beretta USA: Accokeek, MD
With Headquarters or manufacturing facilities in gun friendly States:
Alexander Arms: Radford, Virginia
Browning: Mountain Green, Utah
DPMS: St. Cloud, Minnesota
HK: Columbus, Georgia
Wilson Combat: Berryville, Arkansas
Sig Arms: Exeter, NH
Robinson: Salt Lake City, Utah
Hi Point: Mansfield, Ohio
Knights: Titusville, Florida
Les Baer: LeClaire, Iowa
NAA: Provo, Utah
Bushmaster: Madison, NC
Arsenal: Las Vegas, NV
STI: Georgetown, Texas
CAI: Delray Beach, FL
Noveske: Grants Pass, Oregon
FN USA: McLean, VA
Glock: Smyrna, GA
Daniel Defense: Black Creek, GA
Windham Weaponry: Windham, ME
Remington: Madison, N.C
Ruger: Newport, NH and Prescott, AZ