First is that the .45 Colt is a less-than-stellar lever action round. It'll work alright, but it has a tendency to leak a lot of powder gasses and unburnt powder into the action.
If you want it to feed correctly, you will ditch the SWC bullet and shoot a round-nosed bullet. You may find a SWC bullet that will feed, but many have problems with them.
Try Unique powder, about 8 grains as a max. load. That is standard .45 Colt pressure. Try IMR's Trail Boss or Hodgdon's Clays or Universal Clays as they burn a little cleaner.