Heavy duty retractable blade utility knife

A retractable blade utility knife having a blade receiving opening through one end thereof and comprising a pair of elongated mating handle halves separable along a plane generally extending longitudinally of the knife, a blade carrier having a base for supporting a blade thereon, said blade carrier being mounted between the handle halves for reciprocable movement toward and away from the blade receiving opening to shift a blade mounted thereon between an exposed and sheathed position, one of said handle halves providing a pair of spaced longitudinally extending lands defining a first longitudinal slot, the other of said handle halves defining a mating second longitudinal slot, a blade carrier having a finger piece and a carrier base with an offset extension connected to the carrier base by a necked portion, said necked portion being positioned in said first longitudinal slot with said extension and said base of the blade carrier being disposed on opposite sides of said lands to straddle the same, said finger piece being exposed through said second longitudinal slot and secured to the other of said handle halves for reciprocable movement therein, said finger piece further being secured to said extension thereby to secure the handle halves in assembled relation.