Police seized a home-made gun and $40,000 worth of drugs during raids in Dandenong and Gembrook.
The Dandenong Frontline Tactical Unit executed search warrants during the week of Monday 20 November.
They uncovered a cannabis crop that was due to be harvested, a quantity of methylamphetamine or ice, GHB, cannabis and cash.
The street value of the haul was about $40,000.
Police also found a home-made firearm and ammunition.
They charged a 34-year-old Dandenong man with trafficking methylamphetamine and possessing GHB, cannabis, a handgun and ammunition. He was remanded in custody.
Police also charged a 26-year-old man from Endeavour Hills and a 47-year-old Gembrook man.
They will face court at a later date.
Police urged anyone who knew or suspected someone of dealing drugs to make an anonymous call to Crime Stoppers on 1800 333 000 or a confidential report at www.crimestoppersvic.com.au.
