Stephen Mallen, 36, had fallen out with father-of-three Aaron Freeman, who lived just two doors away in Dudley, over mess he claimed his dog had left on his doorstep, a court heard.
It had led to a heated argument but Mr Freeman had apologised and thought the matter was closed, said Mr Oliver Woolhouse, prosecuting.
However on June 23 last year Mallen brought up the issue again at a barbecue hosted by his next-door neighbour, Wolverhampton Crown Court heard.
Mr Freeman had got talking to the party-goers, including Freeman and another local man Daniel Johnson, also 36, over the fence and brought them out glasses of Ouzo, a Greek spirit, from his house.
But before long Mallen “aggressively” raised the subject that had caused the friction between them two or three years earlier, said Mr Woolhouse.
Mr Freeman tried apologising again but Mallen would not be appeased so he retrieved most of his glasses and retired to sit on his doorstep until the others had finished drinking.
While he waited, Johnson came and sat beside him, laughing, and Mr Freeman could see the barrel of a gun visible from under a white towel on his lap, the court heard.
He panicked and got up to go when he saw Mallen standing on a wall aiming what looked like a long-barrelled shotgun in his direction, the court heard.
Mr Freeman called the police, and Johnson and Mallen were arrested. Police found a black plastic air pistol, airgun pellets, and a replica of a self-loading pistol although no shotgun was recovered.
Mr Freeman, 32, had moved his family out shortly afterwards and suffered from anxiety as a result of the ordeal, the court heard.
Defending Mallen, Mr Justin Roberts said his client had committed an act of “crass stupidity” under the influence of drink.
The defendant, of Heathcliff Road, Dudley, denied any part in the offence but was found guilty after trial of possession of an imitation firearm with intent to cause fear of violence.
He was jailed for 14 months.
Mr Glen Cook, defending Johnson, of Hallchurch Road, Dudley, said he had not been involved in the argument and had not spoken to Mr Freeman.
He pleaded guilty on the day of trial to the same offence and was jailed for 12 months.
Judge Barry Berlin told them: “This was a concerted, calculated effort to terrify this man, and it succeeded.”