Deckard’s sweet gun in Blade Runner was actually built from parts of real guns. Where a lot of prop weapons from films are just resin poured into a mold and then painted, Deckard’s gun looks and feels like a weapon; there’s a genuine heft to it, something inside clicks when you pull the trigger, and there’s even a mechanism for loading it with (non-existent) ammunition.
Source: io9 – We Played With a Perfect Replica of Deckard’s Gun in Blade Runner