A dispensing gun includes a stock having a frame for holding a cartridge, a rod slidably engaged through the stock and having a plunger for moving a viscous material out of the cartridge. A trigger and an actuating plate may move the rod incrementally and forwardly and rearwardly relative to the stock....http://www.google.es/patents/US6691899?utm_source=gb-gplus-sharePatente US6691899 - Dispensing gun having pressure relieving device
