There really is only one powder that is acceptable for 45 Colt and that would be Black Powder. The problem is, once you start using it you'll find yourself putting it in just about everything!!
Having given my two cents worth here's a recommondation for that nasty smokeless stuff:
Somebody in another forum helped me "Discover" Trailboss. The stuff is great for low pressure loads like the old original Black Powder cartridges i.e. 44-40, 45 Colt & 38 Special. It's very fluffy so double charging is almost impossible. Also IMR has data that will allow you to create your own load safely no matter the bullet weight or composition. Basically the stuff is like loading Black Powder in that you can just fill up the case (safely), seat the bullet and go. This
IMRPowder.com link is a 2 page pdf file that enlightened me to the ease with which this stuff loads. Although I still stand by my original powder recommendation (Swiss or Goex), Trailboss is what I use exclusively for loads that can't have the correct powder for whatever reason, like shooting at an indoor range.
Also keep in mind that 45 Colt for the most part is not a cartridge that gets re-sized before reloading. Given the low pressure of 45 Colt (either Black Powder or smokeless), the brass will not normally expand out far enough to make re-sizing necessary. I've got 45 Colt Black Powder brass and 44-40 smokeless brass that has never seen the inside of a re-sizing die. By not re-sizing you will cut down on the amount of "blow-back" in the cylinder and your muzzle velocities will be slightly higher and more consistant. Also, the gun tends to stay cleaner and in the case of Black Powder, cooler.
When you get your brass, I would however recommend re-sizing the first time you load the cartridges. If it's been used by somebody else there's no telling what they fired it out of and if it's new we all know that it isn't always round when it gets to you.
One other thing that I've "discovered" recently is
Bear Creek Bullets, they are moly-lubed lead and you can get them for a decent price in 500 count boxes. I only use them for smokeless but I've been feeding them to everything from 9mm to 44 Special for the last six months.
By the way, did I mention that the only correct powder for 45 Colt is
BLACK??