One needed a only a valid Florida driver's license to purchase a gun in Florida a while back as far as I know. That proves legal residency.
It's a bit more complicated than that.
http://www.atf.gov/publications/newsletters/ffl/ffl-newsletter-2008-11.pdf
If you are a permanent resident (immigrant alien) (have a "green" card), you have to show ID, green card and proof of residency in the state for the last 90 days (utility bills, etc).
If you are NOT a permanent resident (non-immigrant alien) it's a bit more complicated. You have to show proof of residency and have an exception, the most practical of which is a hunting license.
The link shows FEDERAL requirements for residency, state requirements may vary. California, for example, will NOT accept bank statements as proof, even though the Feds will.
Last edited: