I would like to convert my 1873 from straight grip to pistol grip. I wanted to know how Winchester did it. Most factory pistol gripped 1873 seem to be made from straight gripped guns (I may be incorrect). There seems to be a filler piece (which is drilled and tapped for the tang screw) of metal that extends through the lower tang. Does anyone know how Winchester attach this filler piece?

Thanks

Shawn