I've got to disagree with those that think an 1851 can quickly and easily change cylinders. Leave the screw out or loose, and you are going to loose that wedge someplace down the road. First off, the gun ends up in three parts -- are you on a galloping horse? How many hands do you have. Secondly, some place in my pile of stuff, I have an empty box of paper cartridges for the .36 caliber Colt. I reckon while you are looking for the dropped wedge, I'll beat you by using paper cartridges. For those not familiar, the paper cartridge contains the powder and ball. The end of paper tube is ripped off, and the powder dumped in the chamber hole in the cylinder, then the ball is rammed paper and all, and finally the cylinder is capped, and Colt had a really slick brass capper that speed-ed that operation up a lot.
Regarding the Belgium repos, the very first black powder firearm I purchased was a .44 Colt Army Belgium repo, back in 1962. The gunsmith that sold me the gun said it was so exact that original colt parts could be interchanged. I asked him if the repo was that close, how could you tell it was a repo and not get ripped off buying an antique. He told me that the rifling on the originals was a right hand twist, and the repo was a left hand twist. Sounds good, but I don't know the truth of it. No matter, he sold me the gun. I took it out to a burrow pit behind the house, loaded up all six shots, greased the balls to prevent flash over, using Vaseline. Fired the gun and discovered Vaseline melts at to low a temperature. All six shots went off at the same time. I was by myself and you probably could have knocked my eyeballs off with a stick, but I didn't get hurt, and neither did the gun. After that I got some stiffer grease and have never had a problem since. I use water pump grease, but I don't know if you can buy that anymore. Over the years there have been many old and new .44's, but my collection is going bye bye to pay for doctor bills. Old age sucks, the golden years just means all your gold goes out to the doctors.
Regarding flash overs and movies. In the movie "Gettysburg," Lee was trying to flank the Union I believe at little round top, and Chamberlain was in command of the 20th Main, defending that flank. In the movie, the Rebs are advancing up the hill, the Union line is shooting, and the actor playing Chamberlain is standing up, shooting his .44 army, and if flashes across. You got to be quick to see it, but when the gun flashes and all six chambers fire, he turns the gun, and with a shocked look on his face is looking at the pistol wondering what the heck happened. Most people wouldn't catch that, but guys that have had it happen will pick up on it.