I referred to "The Quigley Rifle" as a 45-70.
In the movie it was a Shiloh Sharps 1874 Long Range rifle with a 34" barrel (4"s longer than a standard 30" barrel) converted to fire a .45-110 metallic cartridge with a 540 grain paper-patch bullet. It had double set triggers, and was fitted with a ladder-elevated Vernier peep sight and a Globe front sight.
I have seen the movie 3 or 4 times. It keeps getting better every time I watch it.