The gun, believed to be a viable firearm, was found by officers during routine patrols on November 10, when they noticed a suspicious Ford Fiesta.
Cops stopped the car on Church Vale and arrested the occupants – two men aged 31 and 26 – after finding a gun in the boot, along with a substantial amount of drugs and cash.
Both of the men remain in custody for questioning.
Inspector Jacqueline Nicholson, force CID complex investigation team, said: "We are committed to doing all we can to investigate suspicious activity and in turn getting firearms and drugs off our streets.
"We will continue to carry out patrols and work closely with our communities and partners as part of our ongoing drive to cut violence and save lives across the West Midlands."
Anyone with intelligence about gangs, drugs or weapons is asked to call Crimestoppers anonymously on 0800 555 111.