Following a search of SAS sniper Sgt Danny Nightingale's accommodation and the discovery of the arsenal, he and Soldier N were both summoned to see a superior officer, a court heard.
Timothy Cray prosecuting said: "Soldier N then told the defendant that he had a pistol in his room and ammunition at the property.
"The defendant then said words to the effect 'I've got exactly the same at the house'."
Soldier N later pleaded guilty to Firearms Act offences after a weapon, ammunition and hand grenade were recovered from the property.
He was given a sentence of military detention, which he is serving.