Kid Towne: the Uberti, Cimarron and EMF reproductions of the 1873 Colts, in any form, are better than the originals in that they are made from better metals and have better quality control than the orginals did. But, all that aside, they are probably no stronger or weaker than the original design. They will not stand up to the heavy 45 Colt caliber hunting loads like the Ruger Blackhawks or (basically) or the Vaqueros. However, if you are going CASS, you need not worry about using heavy hunting loads in 45 Colt caliber and the repros will serve you very, very well.
I was in a CASS gun shop last weekend and handle a number of the reproduction models and they are really sweet. If I was going Cowboy, either of the 3 brands I mentioned would be my choice. Actually, I drool considerably over the Cimarrons with their Original Finish or their new Stainless 1873. You can order them with a custom trigger job that enhances their performance a bit in that they use custom parts to maintain tolerances and action fucntioning. Also, they serve well as a field piece with semi-wadcutters, as long as your loads are within original pressure limitations. I would say that a 250 gn swc at anywhere around 850-900'/sec would be a solid defensive load that should also punch through the chest of a whitetail at out to 50 yds. HTH. Mikey.
