I love loading these two Pietta Brassers off the gunA lot of competition shooters prefer to load their cylinders off the gun, as it is faster and easier and easier to be consistent by using an external cylinder loader.
So in competition, with a Remington-style revolver it's easy to pop out the cylinder, load it, and pop it back in.
With Colts you have to take the gun apart.
It can be done (I won national N-SSA medals with a bone-stock Pietta 1860 Army, though with taller front sight blade), but most N-SSA shooters prefer solid-frame revolvers.
They come apart easy , and go back together in seconds. The properly fitted Pietta arbor makes it easy to just lightly tap on the wedge until the arbor is bottomed, for repeatability
I have an 1858 and removing and replacing the cylinder is a PITA, it's easier for me to just break down a pair of well used Colt repros
I would and probably will use one or both of these in a competition of some kind