Good, then you will be well aware of the propensity for the Colt replica's out of the box shooting high, very high. There are some excellent posts on this forum which show how to make corrections to the hammer nose sight to compensate for this. I do not have a 3rd model, but I have a Walker by Uberti that I shoot a lot. If the nipples are the same size, I assume they are, the RWS 1075 size caps are just right and work every time. Load, the chamber diameter I believe will be .448, the cylinder is the same one as the 2nd model Colt. A .451 or .454 round ball will be what you will need. Powder charge - 30 - 35 grains would be your max., you probably won't be able to seat the ball with anything more than 35 gr. I would start out with 25 grains of FFFg, a single felt wad and the .454 ball. This Colt does not have the between nipple hammer rest position which would allow you to load all six chambers and carry "safely". Therefore, my recommendation is that you always look at it as a five shot, not a six shooter, always leaving the chamber under the hammer empty.