Russell Grant-McVicar, 33, carried out eight robberies and one attempted robbery - netting more than pounds 100,000 - between June 1993 and May 1997, James Hines, for the prosecution, said.
Mr Grant-McVicar, who is defending himself, has denied 16 charges of robbery, attempted robbery and firearms offences.
In the raid on the gallery in the West End of London last year, he allegedly travelled there by a black London cab and ordered it to wait as he was collecting a painting. He carried a holdall which concealed a double- barrelled shotgun.
The gallery was housing an original Picasso - Tete de Femme, said the prosecution. The Lefevre gallery specialised in Impressionist and modern painting and was equipped with security cameras and panic alarms. Once inside, Mr Grant-McVicar approached a female member of staff and asked the price of the Picasso, said the prosecution. "When told, he said `I have got a shotgun. I want that painting'," Mr Hines said.
"She was stunned and said `I beg your pardon?' He repeated his demand and reached into the holdall and produced part of the stock of the shotgun. She said `Please, don't take it out'."
The prosecution alleged that Mr Grant-McVicar told her to take the painting off the wall, but when she said she was not allowed to, he ripped the painting off himself.
The case continues today.Reuse content