Knox police officers arrested a man and seized multiple firearms and ammunition after a routine vehicle intercept in Upper Ferntree Gully on Tuesday.
It is understood police intercepted a vehicle on Burwood Highway about 3.15pm.
Checks revealed the driver allegedly had a suspended licence.
It is alleged a small amount of cannabis was located by officers during a search of the car.
A warrant was executed shortly after at a residential property on Olivette Avenue.
Officers allegedly located and seized a double barrel shotgun, a 30-30 Winchester rifle, two imitation firearms, approximately 1300 rounds of ammunition and numerous other prohibited weapons.
Police seized more than 100 grams of what is alleged to be cannabis during the search of the property.
The driver, a 60-year-old Upper Ferntree Gully man, was interviewed and released pending summons.
Anyone with information about illicit firearms is urged to contact Crime Stoppers on 1800 333 000 or make a confidential report at www.crimestoppersvic.com.au