The weapon is a military-style Colt C8 semi-automatic carbine.
Police say the off-duty officer had taken the rifle home for cleaning and left it in his vehicle on April 4 when he went into a restaurant.
While he was inside someone broke into the vehicle and stole the rifle and the ammunition.
Police declined to explain how the weapon was recovered but say no charges have been laid.
The officer who left the rifle inside the vehicle remains suspended with pay.
Also on HuffPost