Gun having disposable cartridge

Claim 1

A gun for spraying flowable material, said gun comprising an elongated tubular barrel having a rear section with a closed rear end and having a separate forward section with an opening extending through its forward end, a forwardly opening tubular nozzle projecting forwardly from the forward end of said barrel and alined substantially with said opening, a disposable tubular cartridge containing said material and positioned removably in said barrel, means securing said rear and forward sections of said barrel together in end-to-end relation and being selectively releasable for the purpose of enabling said cartridge to be inserted into and removed from said barrel, said cartridge being spaced inwardly from said barrel to define a first passage between the cartridge and the barrel, a forwardly opening spout joined to and communicating with the forward end of said cartridge and telescoped through said opening and into said nozzle, said spout being spaced inwardly from said nozzle to define a second passage between the spout and the nozzle, a piston telescoped slidably into and closing the rear portion of said cartridge and being disposable as a unit with the cartridge, said piston being operable, when advanced forwardly, to force said material out of said spout, selectively operable means for admitting air into said first and second passages with the air admitted into said first passage being effective to advance said piston, and means disposed adjacent the forward ends of said nozzle and said spout and coacting with the air admitted into said second passage to cause the material which is forced from said spout to spray out of said nozzle, said last-mentioned means comprising a head telescoped into said nozzle and over said spout and having a centrally located hole extending therethrough to allow material to pass out of said spout and through said head, and a series of holes extending through said head and spaced angularly around said centrally located hole, said series of holes communicating with said second passage to allow pressurized air in said second passage to flow through said head.