text: american residency and handgun ownership.? i am a legal american resident in the state of missouri (a citizen of canada).  can i legally purchase and possess a .40 for the purposes of self defence in the state of missouri? no, it is illegal for an alien to be in possession of a firearm or firearm accessories as per 18 usc 922  it is illegal for an alien whether they are a l.a.p.r or an illegal alien doens't matter.  it still applies to aliens here legally.