Forty-two starting pistols which can be converted to fire live ammunition were handed in to Merseyside Police during an amnesty, the force has revealed.
Olympic .380 BBM revolvers were in April reclassified as a prohibited weapon under the Firearms Act.
Although the Italian-made pistol is commonly used to start races, they are relatively easy to convert.
Merseyside Police said it was pleased with the results of the amnesty.
Supt Richie Davies, from Merseyside Police's Matrix team, said: "While we very rarely see this gun used criminally in Merseyside, any firearm can fall into the wrong hands and have the potential to cause serious injury or even death.
"Merseyside Police will continue to target those individuals who use firearms in the communities of Merseyside and put together a case to prosecute them to the full extent of the law."
The weapon has been prohibited under the 1968 Firearms Act since 4 June and anyone caught possessing it faces a mandatory prison sentence of five years.