Arms are available to most residents of all states.
The question is, "how much hassle will they give you, and what sort of restrictions will they pile up?"
These restrictions come in various flavors, and along various axis. (ie: license to own in some states, not most, license to carry in most states, NFA varies across the board, there's a sprinkling of state level AWBs, some states get their panties in a twist over handguns, but not long guns, etc)
There's some 20,000 odd laws & regulations on the books. Better get reading.
Insanely Restrictive:
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Washington, DC (You can, after much agony, get a license to own a disassembled shotgun locked in a safe in one room of your house.)
Chicago, IL (No handguns, FOID, etc)
Generally Restrictive:
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NJ, NYC, NY, MD, CA, MA, IL
Moderately Restrictive:
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CT
Just about everyone else will weigh in between "gun neutral" and "gun friendly"
VT & AK are by far the friendliest.