23-year-old Daniel Britton of Bermondsey's Lynton Road shot his best friend Dean Cronin.
The shooting took place in John McKenna Walk SE16 on 12 July 2006.
The court heard that Britton had gun magazines in his bedroom, two shotguns and a pistol he kept in the garden.
A jury found Britton guilty of murder at the Old Bailey after a two-week trial.
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