Three men were arrested on Friday during an intelligence-led Police operation at Black Bush Polder, Corentyne, Berbice.
Police said an unlicensed 12-guage shotgun and ammunition were discovered in a storeroom during the operation.
At about 14:05hrs, ranks went to the location and saw two men standing next to a grey 212 motorcar (PNN 3838).
The vehicle was searched but nothing illegal was found.
Police then proceeded to the nearby yard, where the third man was in a storeroom.
The ranks searched the storeroom and found the illegal firearm along with three 12-gauge cartridges.
The police took possession of the firearm, and all three men were arrested as investigations continue.