Over all there were far more Spencers than Hernry's produced. I know I could get hung for this, but I really doubt the Hernry was all that common in the west, it got good press though, thanks to Oliver Winchester. I belive there were 15,000 in round figures made and most were bought by private puchase for Civil War duty. Those who did bring them west would have had to carry lots of ammo cause I doubt that every hardware store carried it till the thens of thousands of 1866's started showin' up, the 66 of course used the same ammo as the Henry.
Slim can ya Google up total production figures for the Spencers.
I am finding conflicting reports on the total production figures from 144,500 to 200,000.
Here is a bit of info that might be interesting.
" After the war, the company could not compete with its own surplus, at the time being sold off by the government. They introduced improved models, but the improvements were subtle. Small civilian, state and foreign orders would not sustain the company, neither would refinishing and spare parts work. Finally, in 1869, the armory closed and was bought by the Fogerty Rifle Company, who in turn were purchased by
Winchester, in a move to lessen competition. 16
16.)Spencer Repeating Firearms, Roy Marcot, Norrthwood Heritage Press 1983, Pg. 155"
http://www.civilwarguns.com/spencer1.htmlSlim