Simon Churchman was charged after police made the discovery at his then cottage in Kirkcudbright, Dumfries and Galloway on March 27, 2018.
The arsenal included seven air guns, a shotgun, a rifle and more than 600 rounds of ammunition.
The 63 year-old today pled guilty to a total of six charges of possessing the weapons and bullets.
Churchman faces a minimum five years in jail for having the Sampoi sub-machine gun.
But, his lawyer told the High Court in Glasgow that she will argue “exceptional circumstances” in a bid to avoid the mandatory prison stint – while name-checking 007.
Lili Prais, defending, said: “His position is that the item was purchased in the 1980s in Tottenham Court Road in London and was bought as a ‘blank’.
“At some point later, Mr Churchman was involved in the James Bond film Die Another Day.
“In the opening scene set in Gibraltar, there is a paintballing exercise carried out.
“He tells me he was involved in giving guidance to those involved in that movie.
“He is an expert in firearms. It is his involvement in that movie which called for this to be modified to discharge paintballs and, in so doing, render it possible to fire bullets.”
The advocate added Churchman also has photographs and paperwork to “support the James Bond proposition”.
Lord Weir continued bail and adjourned the case until next month for evidence to be heard before deciding on sentencing.
The court heard how police had called at Churchman’s detached farm cottage on an unrelated matter before finding a ‘workshop’ upstairs.
Prosecutor Murdoch MacTaggart said Churchman did not have the relevant permission or certificates to have the firearms haul.
The sub machine gun was found to be capable of firing two or more bullets successively without repeated pressure on the trigger.
Mr MacTaggart: “The defence position – which is not accepted – is that this weapon was manufactured to fire blanks only and that Churchman subsequently modified it for the purpose of firing paintballs.”
The gun was found to be in working condition although did “rupture” when tested.
The hearing was told Churchman, now of Whitehaven, Cumbria, was quizzed by police.
Mr MacTaggart: “He remained silent throughout the interview.”
Lord Weir deferred sentencing until September 29 in Dundee.