Pretty sure, no 73's were made in .45 Colt (.44/40instead), however the Pedersoli, Cimmaron and maybe Uberti replicas are chambered in that ctg., seems to me.
With cowboy Action shooting being popular, that rifle is in short supply.

The Uberti '73's also come in .357 Mag., as-do the Cimmaron's.

https://www.b-tactical.com/product/18504...ghtHandFullSize