A clamping tool (10; 10a) for closing C-rings to create hog rings, the tool (10; 10a) comprising: a body comprising a handle and a pneumatic cylinder; a piston movable inside the cylinder, the piston being attached to a piston rod extending from the piston towards a front end of the tool (10; 10a); a movable trigger for activating the piston inside the pneumatic cylinder; a pair of side plates secured to the body, the piston rod being movable between the side plates; a pusher attached to the piston rod for engaging and moving a clamp (88; 88a), the clamp (88; 88a) being fixedly secured to a shaft, said shaft being secured in position by a mounting bracket secured to one of the side plates; two movable jaws (32, 34) pivotally mounted to the side plates; at least one feed roller and at least one one-way clutch bearing, the shaft extending through each of the feed rollers and each of the one-way clutch bearings; a spring biasing the clamp (88; 88a) rearwardly towards the body of the device (10; 10a); a magazine (50; 50a) attached to one of the mounting plates, the magazine (50; 50a) being adapted to receive a plurality of C-rings; wherein upon the trigger being pulled, the pusher moves rearwardly with the piston rod, the spring contacting the clamp (88; 88a) and moving the clamp (88; 88a), shaft, one-way bearings and feed rollers in a counter-clockwise direction, when viewed from the top of the tool (10; 10a), the feed rollers contacting the C-rings to advance the C-rings one at a time into a clamping position from the magazine (50; 50a) and upon release of the trigger, the pusher contacts the clamp (88; 88a) and rotates the clamp (88; 88a) in a clockwise direction, when viewed from the top of the tool (10; 10a), to load the spring for the next pull of the trigger. a body comprising a handle and a pneumatic cylinder; a piston movable inside the cylinder, the piston being attached to a piston rod extending from the piston towards a front end of the tool (10; 10a); a movable trigger for activating the piston inside the pneumatic cylinder; a pair of side plates secured to the body, the piston rod being movable between the side plates; a pusher attached to the piston rod for engaging and moving a clamp (88; 88a), the clamp (88; 88a) being fixedly secured to a shaft, said shaft being secured in position by a mounting bracket secured to one of the side plates; two movable jaws (32, 34) pivotally mounted to the side plates; at least one feed roller and at least one one-way clutch bearing, the shaft extending through each of the feed rollers and each of the one-way clutch bearings; a spring biasing the clamp (88; 88a) rearwardly towards the body of the device (10; 10a); a magazine (50; 50a) attached to one of the mounting plates, the magazine (50; 50a) being adapted to receive a plurality of C-rings; wherein upon the trigger being pulled, the pusher moves rearwardly with the piston rod, the spring contacting the clamp (88; 88a) and moving the clamp (88; 88a), shaft, one-way bearings and feed rollers in a counter-clockwise direction, when viewed from the top of the tool (10; 10a), the feed rollers contacting the C-rings to advance the C-rings one at a time into a clamping position from the magazine (50; 50a) and upon release of the trigger, the pusher contacts the clamp (88; 88a) and rotates the clamp (88; 88a) in a clockwise direction, when viewed from the top of the tool (10; 10a), to load the spring for the next pull of the trigger.