.45 Colt pistol round is the same as the .45 LC round. The .45 ACP is a rimless round designed for the 1911 and should not be confused as the same round.
Technically there is no such thing as a .45 LC round but you will see it described as such.
Winchester has Cowboy action load .45 Colt USA45CB that is a 250 grain lead flat nose. Will work well in your rifle. I picked up a couple of cases 2 years ago [600 rounds per case] for $12 per 50. They are not priced anywhere close to that anymore.
This is one caliber that reloading will save you TONS of money. I believe they sell for $17 to around $24 a box now.
. Cases can be used over and over and over as long as you don't go nuts with the velocity. [You can load them up HOT for use in a Casull or a [OLDER ONLY!!!] Vanquero. [New ones are NOT as stout as far as I am concerned and any of the SAA Colts are verboten with hot loads]