According to HWS volume 1, starting on page 199:
Prior to 1880 405 grain bullets were standard for both the rifle load (70 grains of black powder) and the carbine (55 grains of powder) which resulted in use of R or C on the headstamp to distinguish between them.
In 1880 experiments started on the 2.4 inch “lengthened” case (compared to the normal 2.1 inch .45-70 case) and was adopted in 1881, with several variations over the next 2-3 years, all for use in “sharpshooters” or more correctly target match use. (The longer .24 inch case was mainly for use in about 150 special rifles, not the several hundred thousand standard service rifles.)
In 1882 the “Caliber .45 Rifle Ball Reloading Model 1882 Cartridge” was adopted with a 500 grain bullet using Boxer primed cases. However, manufacture of 405 grain bullet cartridges and both 405 and 500 grain using the old internal primed cases continued well into 1882.
Subsequent models used the 500 grain bullets for rifle loads:
Model 1886 which used the Morse type detachable base
Model 1888 with tinned brass case
Model 1898 with smokeless powder and therefore a seating cannelure in the case.