Here you go
https://docs.google.com/document/d/1c7UkkNyMTZ9NAztILpzjSLKvgIneAw5i7eqkZ3d3Eno/edit

Shooting styles varied. Some turn-of-the-century wing shooters shot with an erect neck, others crawled the stock.

[Linked Image from photos.smugmug.com]

Part of the confusion is that many old images showed the shooter in the 'ready' position, not as they were pulling the trigger

[Linked Image from photos.smugmug.com]

Clearly Live Bird and Inanimate Target guns had dimensions similar to those of today, except for the fact that shooters today are taller and much heavier than they were in 1900.
24 year old Union soldier in 1860 - 5’ 8” and 143.5#
22 year old American soldier in 1955 - 5' 8" and 150.2#
50th percentile for American 25 year old men in 2002 - 5’ 10” and 168#

In an August 2016 report from the U.S. Centers for Disease Control and Prevention's National Center for Health Statistics, the average weight of men in the United States rose from 181 pounds 1988 - 1994 to 196 pounds 2011-2014. Their average height remained the same at about 5 feet, 9 inches.
The average woman expanded from 152 pounds to 169 pounds while her height remained steady at just under 5 feet, 4 inches.