Ammu*Nation

Ammu-Nation is a Gun Store and is a common weapon store in Liberty City

It is also the First Gun Store Available in The Final Remnant.

Weapons Available (Final Remnant)
Ammu Nation is the only Legal Firearms Dealer throughout Liberty City. which is why they do not have Strong weapons.

Store at Alderney during the chapter one of the story. New Weapons at Chapter Two

Trivia

 * The M1 Thompson SMG is not available in Grand Theft Auto series but can only be seen as a background design in the Ammu-Nation at San Andreas.