An endoscopic needle knife may include a collet coupled to a distal end of a tubular member of the needle knife. A cutting wire may be disposed within a cutting wire lumen of the tubular member and a central lumen of the collet. An inner surface of the collet body may create a frictional force between the cutting wire and the inner surface so that the cutting wire is resistant to longitudinal movement relative to the tubular member caused by external forces. The frictional force may also be less than a longitudinal force exerted on the cutting wire by a handle assembly or other control mechanism that is used to longitudinally move the cutting wire within the tubular member and the collet.
