A delivery device for semi-solid implantable material such as synthetic bone graft substitutes. The device includes a handle, a cylinder extending from the handle and having an outlet at its distal end. A piston is operated by a trigger and is slidable within the cylinder to displace the material from the cylinder. The cylinder has a substantially constant inner diameter along its entire length such that the outlet has substantially the same inner diameter as the rest of the cylinder. When the trigger is fully depressed, a ratchet mechanism is disengaged allowing the piston to be pulled back to a starting position.