A man threatened police officers with a handgun and rammed them with a van, ordering them to "get out of my house".
Officers had attended the home of Thomas Whelan, in Orchard Street, Newthorpe, following a concern for his safety on June 8 last year.
Whelan had gone upstairs to get his mobile phone while the officers were contacting support agencies, but when he came down, he was pointing a black handgun at the officers while shouting the demand.
The officers ran outside and sought cover behind a police car but Whelan followed them, got into a van and started ramming the two police cars.
The officers were able to seek cover in a neighbouring house when armed response arrived.
The van was located and armed officers used tactical contact to bring it to a stop. Whelan, 57, was pulled out of the vehicle and arrested.
Officers also found a black BB revolver in the foot well and a shotgun was recovered from his home, along with a large amount of cash.
Appearing at Nottingham Crown Court on July 8, Whelan pleaded guilty to possessing an imitation firearm with intent to cause fear of violence.
He also admitted possessing a firearm without a certificate, two counts of having a bladed article in a public place, dangerous driving, driving without a licence and without insurance.
The judge sentenced him to three-and-a-half years in prison.
Detective Constable Tim Baker, who led the investigation, said: "Clearly we recognise that Whelan was suffering from mental health issues when officers visited him that day but we cannot condone this violent and abusive behaviour.
"The officers were just trying to help him.
"It's also clear that he was conducting criminal activity by having the illegal firearms in his home.
"To our mind, he is a dangerous individual and we're glad he has been held to account for his crimes."
