Olympic hopeful James Huckle had to settle for 40th place in the 10 metre air rifle as the ISSF World Cup continued at The Royal Artillery Barracks.
Huckle finished 22 places ahead of fellow GB competitor Kenny Parr in an event won by Frenchman Pierre Edmond Piasecki.
Piasecki, 26, came out on top in a youthful final.
The silver medal went to 22-year-old Sergy Rikhter of Israel, with Belarussian Illa Charheika, 19, taking bronze.
"It's great to be shooting here in London, on the Olympic venue," said Charheika after the medal ceremony.
"I really hope I will be back in this final hall in July, at the Olympics."