Around 9pm on Saturday (3/1/15) Police say they attended an address on Place Rd in Woorree, conducting inquiries into an unlicensed firearm.
There they found a short barrelled firearm wrapped inside a pillowcase and sheet, under a bush near the back patio.
A 23 year old man was arrested and charged with possessing a controlled weapon.
He will face the Geraldton Magistrates Court on Monday 5 Jan 2015.
Police say the replica firearm has been assembled from parts of other firearms.
WA Police have in the past expressed some of the dangers of replica firearms as they can with little effort be modified to fire a live round.
Under section 10 in schedule II of the WEAPONS REGULATIONS 1999, imitation firearms are "Controlled Weapons".
10. Imitation firearm
An article, not being an article that is clearly a toy, that has the appearance of being a firearm but is not capable of discharging a missile.