The inventive ablation element comprises an elongated cannula having a proximal end and a distal end. The gun comprises a body defining a bore therethrough; a moveable member positioned at least partially within the bore; and a nozzle assembly coupled with the body and positioned at a bore opening. When the deformation from the state of applying a load of 98N to a load of 1274N to the center is A, and the deformation from the state of applying a load of 98N to a load of 1274N to a thread-wound core having rubber thread wound around the center is B, the difference is 0.