Mark Hughes, 23, from Buckley, admitted to the possession of a sawn off shotgun and stun gun last summer, as well as drugs offences.
He said he found the weapons while digging in his grandparents' garden.
But that was dismissed as "utter nonsense" by Judge Rhys Rowlands at Mold Crown Court.
Hughes was found in possession of the double barrelled 60cm (24 inch) shot gun and the stun gun - which gives off an electrical charge - on 31 July 2016.
Both were in working order.
He told the court he had the weapons as he was considering taking his own life.
Judge Rowlands said it was a sad case and it was clear Hughes had suffered a very unpleasant injury.
But he dismissed his claim of finding the weapons in a garden.
He told Hughes: "You are addressing a very keen gardener. I don't come across weapons in my garden and I suspect no one else does either".
Judge Rowlands added that Hughes may well have considered harming himself, but if he persisted with his claims of how he came by the weapons, evidence would have to be called. He would then lose credit in sentencing.
Hughes will be sentenced next month.
A Flintshire man who shot himself in the foot has been told to expect a long prison sentence.