A "Quigley" load is a long range match load. Many people use 45-70, But the movie rifle is 45-110!
I have Four 45-70 rifles. My Shiloe Sharpe's 1874 only gets fed Black Powder loads. My Marlin Guide Gun (18") and my Browning 1886 (26") both enjoy the following load as a plinker:
WW Brass
WLP primer (Yes that is Large Pistol)
300 grain Moly Coated Bear Creek Bullet
14.0 gr. IMR Trail Boss powder
Listed velocity 1285 fps (20,900 CUP)
Actual velocity in the 26" barrel 1325 fps.
Iron sight accuracy- 200 yards, 1.25" 5 shot group off a sand bag
Source; 2006 IMR Smokeless Powder Guide
Comments, You can easily get 45-70 much faster than Black Powder Velocities! But for your 500 grain bullets, 1300 fps muzzle velocity, will be an extremely accurate load. As for Energy, BP loads killed Buffalo to the point of extinction! The 45-90, 45-100, & 45-110 extended the range, not the lethality.
Winchester & Remington sold their ammo by Caliber- Charge weight- Bullet weight. Ex: 45-70-405
Sharps sold empty brass and rifles by the chamber dimension; ammo was sold with several different systems.
45-70 = 45-2 1/10"
45-90 = 45-2 4/10"
45-100 = 45-2 6/10"
45-110 = 45-2 7/8"
45-120 = 45-3 1/4"
Ivan