Thanks for the link to that article.
After reading and researching a little more, I still think "Bo Dorn's" Crossfire rifle
wasn't in .45/70.
The article that link goes to says the Remington-Keene was chambered in .45/70, but also the .43 Spanish
cartidge and one other round I can't remember as I post this. Both of the latter rounds had creases in the casings, something "Dorn's" ammo didn't have.
I still think Dorn was using something like a .40-60 round in his rifle. The .45/70 is frequently almost as long as one's finger, but the round I saw in the Crossfire flick
was much shorter than a .45/70 and more slender.
When googling cartridges, I came across a fellow making .40-60's from .40-65 brass. He was cutting off almost a 1/2 inch of the 40-65's case. For anyone interested!