A year or two ago, Missouri scrapped all their state gun laws and they just operate on the Federal Default rules. I am a permanent resident alien, if I buy in Missouri, the only ID is my driver's license and they make me wait 48-72 hours. If I buy next door in Kansas, they make me wait, and they require 3 consecutive documents, dated 1 month apart, with your name and address on it, something like three most recent phone bills, 3 most rcent electric bills etc.
My living rent free in the basement of my ex-wife's place, I have no utility bills. Olathe Gun Shop is holding a rifle until I get the three documents in order, but I decided I will get my money back and buy in a Missouri store or from a private party.