The picture on the bottom of page 270 of the second edition of Walter's book shows an early NIG trigger guard with the same short back strap as your gun, with one screw. It appears someone has added a second screw to your gun obliterating the last two digits of the serial number. Later NIGs, as is shown at the bottom of page 269, have a much longer backstrap, similar to a Flues Model hammerless, with two screws.

Last edited by Researcher; 10/23/11 08:37 PM.