Seven people have been arrested following the discovery of the items buried up to 2ft underground in land behind Rathgar Road, Loughborough Junction.
Police spent three days searching the site last week. They found fresh cannabis buds, a “large amount” of crack cocaine, 37 rounds of 9mm ammunition and the single-barreled shotgun, hidden in subterranean tubs.
Det sgt Stephen Payne, who led the search, said: “It took three days of hard work and perseverance to go over every inch of the land but was worth while as the items recovered are a good step in disrupting the criminal activity they may have been used for.
He added: “Our officers will continue to use their specialist skills and expertise to fight the war on crime.”
Residents reported a high level of police activity in the area all last week as search specialists were brought in to uncover the haul.
They found holes cut in a fence between the wasteland and an industrial unit in Rathgar Road, which helped lead to the arrests.
The seven men arrested, all from south London and aged between 37 and 64-years-old have been bailed to return to a police station next month.