Abstract: A pair of generally superposed, elongated horizontal upper and lower jaw members are provided including rear ends tightly joined together and vertically divergent front ends equipped with inwardly projecting and opposing cutting edges is provided. A generally rectangular bail having upper and lower arms disposed above and below the front ends of the upper and lower jaw members is provided and includes upstanding opposite side arms interconnecting corresponding ends of the upper and lower arms. The lower arm is supported from the transverse midportion of the front end of the lower jaw member by mounting structure mounted for angular displacement about an upstanding axis and for angular displacement of the lower arm relative to the mounting structure about an axis substantially coinciding with the longitudinal center axis of the lower arm.