Abstract: A caulking gun including a barrel having a dispensing tip on the outer end and a mechanism for releasably connecting the tip in sealing engagement with the outer end of the barrel. The barrel has a handle mounted on the inner end thereof with a trigger pivotally mounted on the handle. A rod extends within and from the inner end of the barrel with a piston on the rod and within the barrel. A dog having a hole therethrough and through which the rod extends to allow canting movement of the dog on the rod. The trigger has a lug thereon for engagement with one end of the dog to cant the dog in one direction on the rod to grip and advance the rod and the piston thereon in the barrel as the trigger is pivotally actuated. The handle carries a mechanism for canting the dog in the other direction free of gripping engagement with the rod when the rod is moved into the barrel whereby the rod and the piston thereon may be withdrawn from the barrel free of the dog for filling of the barrel.