This is an E. Schmidt & Habermann blitz drilling as seen on NE and on Chapmen's(Mike Hammer) site. I realize we are considering a double and not a triple, which has the large bar in the centre under the lower striker being just forward of the hammers. Doubles have separate dogs and typically they are held by a pin/screw on the side of the frame.

Kind Regards,

Raimey
rse