A Waikato man has shot himself in the leg while allegedly trying to hide a gun from police.

Police were called to reports of shots being fired on a farm bordering bush at Waitekauri, near Waikino, about 9.40pm on Friday.

"The landowners advised no-one had permission to be shooting on their land and police converged on the area which is accessed via Waikino, between Paeroa and Waihi," Sergeant Jim Corbett of the Thames Strategic Traffic Unit said.

"About an hour after the initial report of shots being fired a car approached a police checkpoint on Golden Cross Rd, as the vehicle came to a stop the front seat passenger got out of the car and appeared to have shot himself in the leg as he went to get rid of a .22 pistol he had concealed down the front of his pants."

Corbett said despite his injury the man was still able to throw the firearm into scrub.

"The man was treated for his wound by police at the scene before being taken to Waikato hospital. However we understand the 35-year-old discharged himself with the projectile [bullet] still embedded in his leg but he is expected to return there today to have it removed."

Corbett said they would interview the man following his treatment, but in the meantime there were a number of lessons to be learned.

"We've already mentioned the man didn't have the landowner's authority to be shooting on the property, it is also unlawful to shoot in a state forest, forest park or national park during the hours of darkness.

"It is also unlawful to be using a firearm without a licence or to carry a loaded firearm in a vehicle. Given the occupants of the vehicle approached a police checkpoint with a loaded firearm this incident could have had far more tragic circumstances," said Corbett.

Anyone wanting further information on firearms safety is advised to contact the Waikato Police District's Firearms Officer on 07 858 6200 or their local New Zealand Mountain Safety Council branch or local gun club.