Pneumatically operated spear gun

A spear gun (10) for underwater fishing and like purposes comprising a gun barrel (14), a pneumatic valve means (16, 24) secured (24) to the rear end (16) of said barrel (14) permitting a desired air pressure to be provided therethrough into said barrel, a valve protecting cap (20) threaded over said barrel rear end (16), a gun stock (28) secured (30, 32) about said gun barrel (14), a piston (58) fitting snugly yet slidably within said gun barrel, said piston (58) having a plurality of O-ring piston grooves (60) and O-rings (64) therein spaced apart along its cylindrical surface and a lubrication groove (62) intermediate each pair of O-ring piston grooves (62) maintaining the pressure in said barrel (14), said discharge end of said gun barrel (14) being externally threaded (49), a cylindrical bored plug (55) threaded at one end on said externally threaded discharge end (49) of said barrel, a bored head (56) having its rear end threadedly secured to the other end of said plug (55), a spear (13) having a cylindrical rod extendable through said bored plug (56) and through said bored head (55) into contact with the forward end (68) of said piston (58), said spear rod (12) having a conically reduced portion (84) adjacent to but spaced from its spearing end (94) providing a radial shoulder (86) facing toward said spearing end, said spearing end being threaded (94) to receive and secure a harpoon hook (96) thereon, a V-shaped spear lock (74) secured in said bored head (56) adjacent its bore to pivot (72) its upper tine (73) against said conical portion (84) of said spear rod (14) to abut said spear rod radial shoulder (86) when said shoulder is positioned thereagainst, an L-shaped sear (78) pivotally (76) secured in said head (56) with its upper L-leg (80) extending into the mouth of the V of said V-shaped spear lock (74) and with its other L-leg (82) extending externally of and below said head (56), a trigger rod (40) pivoted (83) at one end to said externally extending L-leg (82), the other end of said trigger rod (40) providing a trigger (34) extendable partly (36) into said gun stock (28), an eccentric trigger locking and releasing cam (42) pivoted (44) in said gun stock (28) and a manually operable lever handle (46) secured to said cam (42) extending externally of said gun stock (28) for rotating said cam to abut said trigger (34) and lock it against operation or for rotating it away from said trigger (34) for releasing said trigger for operation, a pair of spaced apart rings (50) secured (51) on said barrel (14) supporting depending bearings (48) about said trigger rod (40) through which said trigger rod may be freely reciprocated, a trigger spring (52) biased against one of said bearings (48) and against an abutment (53) secured to said trigger rod (40) biasing said trigger rod to spear rod locking position (73 and 86) whereby when said gun barrel has been pressurized (66) through said pneumatic valve (22) to the desired pressure, said spear rod (12) may be manually inserted and pressed against said piston (58) to push said piston against the pressure (66) in said gun barrel (14) to move said spear rod (14) into the gun barrel (14) until said trigger spring (52) biases said sear (78) to actuate said spear lock (74) into spear rod locking position abutting against said spear rod radial shoulder (86), and when said trigger (34) is pulled, after said eccentric cam has been rotated to the trigger releasing position, said spear lock (74) will release said spear rod (12) to be ejected from said gun barrel (14) under the pressure (66) in said gun barrel (14), said pressure (66) remaining substantially unimpaired in said barrel for subsequent operations of said spear gun.