Three suspects were arrested on Friday while trying to sell a rifle to an unsuspecting buyer in Songot area, Lokichoggio, Turkana County.
The three had approached a buyer and offered him an AK47 rifle with an empty magazine when undercover police struck.
Police said the three include a 19-year-old man and two aged 20 respectively.
The weapon did not have a serial number at the time of its recovery, police said.
The three were detained at a local police station pending an investigation into the source of the weapon and motive.
Police want to establish if the men have been engaged in similar business in the past.
Illegal weapons in the region have been blamed for increased cases of banditry. The operations have led to a drop in such attacks in general, statistics show.
This has led to less development and deaths in general.
The government has increased operations to address the menace.
Meanwhile, a worker recovered 17 bullets from a farm he was clearing in Ngoriga, Njoro area, Nakuru County.
The worker told police he was clearing bushes from the farm when he stumbled on a plastic container that had been partially buried.
On checking its contents, he discovered it had 17 live bullets.
Police were called to the scene and picked up the cargo for investigations.
The owner of the land was away at the time of the discovery, police said adding they are investigating the issue.
In Thika, Kiambu County, police recovered 20 live ammunition in an operation on a home in the Umoja area on Friday.
Police said they had been tipped off that the occupant of the house had illegal weapons prompting the operation.
Apart from the bullets, the officers recovered a kilo of bhang, 20 litres of ethanol and 58 military packs.
Police said they arrested two suspects in connection with the recovery as investigations on the motive go on.
