A metal-stretching grip head has a row of parallel upper plates wholly to one side of a plane and having front ends and rear ends and a row of parallel lower plates wholly to an opposite side of the plane and having front ends forming at the plane with the front ends of the upper plates a mouth slot extending along the plane and open forwardly on the plane. The lower plates also have rear ends juxtaposed across the plane with the upper-plate rear ends. A one-piece C-section metal bar is snugly received in the mouth slot. Rigid structure separate from the plates and bar fixes the plates relative to one another.