The identifying evidence, which I had seen before, is the "notch"
on the rear of the hammer. Its not really a notch, but rather the
boundary of the re-contouring of the lower curved part of the back
of the hammer.

Relocating the hammer stud in this fashion causes two different
things to happen. One is that as the hammer now has a rearward
movement as it is cocked; ie, as it rotates it is also moving rearward.
The second is that, because of this rearward motion, it releases
earlier; ie, the double-action sear falls off the trigger sooner, and this
is what really gives it the shorter throw.

I would presume this was done before the factory developed the
short-throw action. King Gunsight was the one who pioneered the
larger adjustable sights, and the wider hammer spur - he called it
double-cockeyed. He, and/or perhaps others, developed the idea of
the shorter throw.

Even target stocks were not developed by the factory. Many of the
well-known shooters of the 1910's and 1920's were augmenting the
small relatively-narrow stocks with additional material. Ed McGivern
figured out that Kearserge was making a grip that fit his hand
properly, and thus developed the McGivern model Kearserge stock.

The LAPD were the real modern innovators of target stocks. Its
debateable who was first - it appears to have been Walter Stark, one
of the LAPF armorers. His deciples (sic?) like Farrant, Hogue, and
many others at LAPD really pushed the developement of target stocks.

We are all admirers of the factory, but a lot of the really innovative
ideas came from elsewhere.

Mike Priwer