The turned pin and buggered screws are unfortunate, and suggest someone worked on the gun without the expertise to do so.
For interest, this is a Parker SBT introduction ad in the April 1917
Illustrated Outdoor World and Recreation
https://books.google.com/books?id=gX87AQAAMAAJ&pg=PA148
1918 with a grooved FE which I'm not sure anyone has actually seen
The Morgan pad was introduced about 1932
