Officers working on a tip obtained a warrant to search the Forest Avenue home in the Morrisania section.
The assault rifle was recovered inside of an unlocked closet covered by a blue T-shirt.
Police also recovered 62 rounds of ammunition from the inside of a plastic case located next to a couch.
The three suspects, identified as 27-year-old Steven Walker, 23-year-old Victoria Velez and 24-year-old Emmanuel Rosado, were arrested and charged with four counts each of criminal possession of a weapon.
All three suspects lived at the address.