Thanks!
I tend to be obsessive about researching things I have interest in!
Back in the early 80's, when I first got into Buckskinning... I read just about everything I could find on the Fur Trade and the Mountain Men... including artwork of John Catlin and Alfred Jacob Miller... who captured the visuals of the time.
Likewise with Cowboy Action Shooting in the early 90's... with the added benefit that photography was present in the late 19th Century.
While researching the Mares Leg prior to purchasing, I found many forum threads full of "I heard" rumors, and opinions.
Generally, I found the majority of negative views were from pundits that never owned... and many that never fired a Mares Leg.
However, the majority of the pundits that had a positive views owned, or at least had fired a Mares Leg.
Although I could not find any record of a period Mares Leg converted Carbine, Winchester did make 12" barrel 1892 Carbines (Cody affirmed).
There was no shortage of sawed off shotguns, or "Street Howitzers".
Like wise, there was no shortage of revolvers with detachable buttstocks... and revolver action based Carbines!
So... the crossover between long arm, and handgun did exist in the period.
And... I can imagine a Carbine breaking the buttstock off at the wrist... and getting an expedient repair of wrapping the tang with rawhide!
The best reference I could find on the original Mares Legs (3) was in a 1961 Guns Quarterly Article. 1961 was the last year of the series, and Steve McQueen was available for corroboration:
http://www.originalprop.com/blog/20...-mcqueens-prop-gun-from-wanted-dead-or-alive/