Asher Maylor opened fire after a ‘falling out’ with Andrew Bell whom he had known for almost a dozen years, Stafford Crown Court heard.
The pair were among several men seen arriving at and leaving the flat in Chervil Rise, Heath Town, Wolverhampton, where the shooting took place on March 10 last year.
The defendant and others at the address fled from the scene, leaving the seriously injured victim without alerting the emergency services.
But a neighbour raised the alarm and Mr Bell was taken to hospital with ‘multiple’ pieces of lead shot and wadding embedded in his right thigh. He was left scarred for life.
It was claimed he had been gunned down because the 33-year-old defendant had been ‘disrespected’ but this was dismissed by Judge Michael Chambers QC.
Maylor has not provided an explanation.
He gave a ‘no comment’ interview to police after his arrest and chose not to give evidence during his trial which ended with him being convicted of possession of a firearm with intent to endanger life and causing grievous bodily harm with intent.
Judge Chambers said: “There is clearly more to this incident than we have been told.
"This was a retribution shooting in the context of some form of serious criminality but it cannot be said to have been gang-related.”
Maylor, from Greensome Court, Stafford, had a string of previous convictions including possession of a prohibited firearm.
The judge ruled he was so dangerous that only an extended sentence would do.
Maylor was jailed for 15 years and must serve at least two thirds of that behind bars before being able to apply for parole.