Do you happen to have dies to handload the .44-40? Unless you have someone nearby to load rounds for you, Ten-X in the U.S.A. is about the only game in town. Currently, they are $47 per box of 50, and whatever shipping and hoops to get it here.
My .44-40 black powder loads are the Lyman 427666 lubed with SPG. 33 grains of Goex FFg trickled using a drop tube into a Winchester case with a 0.030" thick vegtable fibre gasket wad over the primer, then a Winchester Large Pistol primer. I use this in all of my original .44-40's and it seems to work well. Cleanup consists of flushing the bore with hot soapy water delivered via a "bore bong". Take a spare case, drill it out to accept a length of hose, then fit a funnel on. Cuts down cleaning patch usage by half. Then turn rifle upside down and clean from the muzzle using Windex with Vinegar (not Ammonia). Then drypatch and give a coat of your favourite rust preventitive. Cases are de-primed, soaked in hot soapy water, then tumbled in a ceramic media tumbler. Corn cob works, but it does dirty the media something fierce. It's just as much fun as it is work.
I would love to help you out, but I'm not interested in loading ammo for others due to liabity issues.