Police have seized dozens of handguns and more than 1000 rounds of ammunition as part of an investigation into replica and blank firing firearms being converted into working order.

Fremantle Detectives will allege a 56-year-old man was modifying replica firearms and converting them to "live working order" in exchange for drugs and ammunition.

The haul of weapons which were seized. Credit:WA Police

On Thursday detectives executed a search warrant at a home on Pearse Road in Beeliar. During the search it is alleged police found:

Fifteen replica and blank firing handguns that were in various stages of modification, four of which had been fully converted to fire live ammunition.

More than 1000 rounds of ammunition;

Various prohibited weapons;

Firearm silencers;

Small amounts of methamphetamine; and

Metal working equipment used to modify firearms.

The 56-year-old man is facing a string of drugs and weapons charges including 13 counts of unlicensed person possess firearm/ammunition, four counts of possessed a prohibited weapon and possess a prohibited drug.

He will appear in the Fremantle Magistrates Court later this month.