BTW we discussed this in 2015, with contributions from Researcher but the images were on Photobucket and are lost
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=389279&page=all

THIS is interesting
https://books.google.com/books?id=YqJbN1-TtXMC&pg=PA59&lpg
A BTFE on a Parker A1S double SN171598 in 1915?? Maybe someone could look up the SN in TPS?

"Beaver Tail Forend" on a rifle, 1921
https://books.google.com/books?id=gJkwAQAAMAAJ&pg=PA701&lpg

Iver Johnson Special Double Trap with "Beaver Tail Forend" 1922
https://books.google.com/books?id=JCkkAQAAMAAJ&pg=PA68-IA2&lpg