A former soldier who handed a discarded shotgun in to police faces at least five years imprisonment for "doing his duty".
Paul Clarke, 27, was found guilty of possessing a firearm at Guildford Crown Court on Tuesday – after finding the gun and handing it personally to police officers on March 20 this year.
The jury took 20 minutes to make its conviction, and Mr Clarke now faces a minimum of five year's imprisonment for handing in the weapon.
In a statement read out in court, Mr Clarke said: "I didn't think for one moment I would be arrested.
"I thought it was my duty to hand it in and get it off the streets."
The court heard how Mr Clarke was on the balcony of his home in Nailsworth Crescent, Merstham, when he spotted a black bin liner at the bottom of his garden.
In his statement, he said: "I took it indoors and inside found a shorn-off shotgun and two cartridges.
"I didn't know what to do, so the next morning I rang the Chief Superintendent, Adrian Harper, and asked if I could pop in and see him.
"At the police station, I took the gun out of the bag and placed it on the table so it was pointing towards the wall."
Mr Clarke was then arrested immediately for possession of a firearm at Reigate police station, and taken to the cells.
Defending, Lionel Blackman told the jury Mr Clarke's garden backs onto a public green field, and his garden wall is significantly lower than his neighbours.
He also showed jurors a leaflet printed by Surrey Police explaining to citizens what they can do at a police station, which included "reporting found firearms".
Quizzing officer Garnett, who arrested Mr Clarke, he asked: "Are you aware of any notice issued by Surrey Police, or any publicity given to, telling citizens that if they find a firearm the only thing they should do is not touch it, report it by telephone, and not take it into a police station?"
To which, Mr Garnett replied: "No, I don't believe so."
Prosecuting, Brian Stalk, explained to the jury that possession of a firearm was a "strict liability" charge – therefore Mr Clarke's allegedly honest intent was irrelevant.
Just by having the gun in his possession he was guilty of the charge, and has no defence in law against it, he added.
But despite this, Mr Blackman urged members of the jury to consider how they would respond if they found a gun.
He said: "This is a very small case with a very big principle.
"You could be walking to a railway station on the way to work and find a firearm in a bin in the park.
"Is it unreasonable to take it to the police station?"
Paul Clarke will be sentenced on December 11.
Judge Christopher Critchlow said: "This is an unusual case, but in law there is no dispute that Mr Clarke has no defence to this charge.