Black powder .45-70 cartridges

[Wijbrandus]

Ok, this may be a really stupid question, but I've got to ask.

I've got a Marlin 1895 Cowboy.  I've been shooting regular old Ultramax ammo in it while I get used to it, since I've only had it a few weeks.

A gentleman I talked to at the range was admiring my rifle, and wanted to know why I wasn't firing black powder ammunition in it.

First off, I don't know if I can do this without making a mess of my rifle.  

Second, I don't know where to find the ammo.

Third, I don't know if this is something I even want to do, but it sounds kind of neat.  If I could find someone who makes .45/70/500 ammunition like the old cavalry used, I'd certainly like to try it.  But then, I don't want to mess up my rifle.

And on a related tangent, is there a problem firing all-lead bullets and jacketed bullets through the same barrel?  Or do I need to take some precautions?

Any expert advice out there?

[John Y Cannuck]

Firing a copper round through after a few (Note few) black powder rounds will help clean the bore. It may be that black powder fouling could raise pressures if you let it build up then fire a jacketted smokeless round.
I fire limited numers of Black powder rounds through my 1886 Win. No problems, I just fire a few smokeless rounds, then clean as usual. Be sure to clean the action as well.

[Sweetwater Jack]

Good info. Especially Gatofeo's post.  All I'd add is to get a .45 cal BoreSnake for on the range cleaning.  I spray Ballistol on the boresnake and run it through from breech to muzzle after about 20 rounds. The Ballistol is one of the best lubricants around for B/P and Mixed 1 part Ballistol to 10 parts hot water is a super cleaner.  Stay away from petroleum-based lubricants for black powder, both as bullet lubes and cleaners.

[Flint]

Watch the overall length, especially in a Marlin.  The lifter will only accept a certain overall length, and will feed a 300 or 350 grain bullet well.  There are 400 grain bullets with a crimping groove farther forward that will work, but most 500 grain bullets have too long a nose, and were designed for single shot rifles.