A man was arrested after police searched his house in Muang district and found two illegal firearms on Wednesday.
Pol Col Serm Kwannimit, deputy provincial police chief, said police acted on information that military grade weapons were being sold from the premises.
They found an HK-47 assault rifle and a 9mm Llama pistol inside a wooden cupboard with a keycard lock.
Teeradet “Bang Jack” Chuhai, 20, was in the house. He was arrested and charged with possession of illegal weapons with intent to sell.
Mr Teeradet allegedly confessed the guns belonged to him. He said he ordered them from Bangkok. The rifle cost 40,000 baht and the pistol 43,000 baht. The weapons were sent to him by a private delivery service.
Police were investigating further.