This gun was found as police raided properties across Hounslow in the latest Operation Big Wing crackdown.
Officers also recovered 34 wraps of suspected heroin and a quantity of suspected crack cocaine during yesterday's (Thursday, July 24) day of action.
Police searched nine properties across the borough, at one of which, in the Hounslow East area, they found this handgun.
They arrested 17 people, including three who were on warrant, three suspected drug dealers and one on suspicion of causing grievous bodily harm (GBH).
On the roads, three cars were seized for being uninsured and 15 drivers were reported for various traffic offences.
Meanwhile, Hounslow Police Cadets again went undercover at shops, one of which was reported for selling a knife to someone aged under 18.
Chief Superintendent Carl Bussey, Hounslow's borough commander, said: "Anyone looking at today's results can be assured that Hounslow Police are working hard to bring those responsible for crime to account.
"This was a well organised operation that yielded the results our community wants to see: criminals arrested and held to account.
"We do not tolerate criminal activity in Hounslow; those who think that Hounslow is a place to commit crime have just cause to think again."