This is a new cylinder and has a single loading gate and firing pin. Pretty cool stuff.
When you get your revolver, measure the cylinder mouth diameters - all 6 of them and record the numbers. Measure the groove to groove diameter as well.
The cylinder should be .001" to .002" larger than the groove diameter, then you use a ball that is about .003" to .004" larger than the new cylinder diameter. If the mouth of the cylinder has nicely rounded & smooth corner, instead of sharp, when you seat the ball, it will draw(swage) into the chamber and not shave. This will give an even tighter fit into the cylinder & LENGTHEN the ball slightly, also improving accuracy.
Once these changes are made, this cap 'n ball revolver will shoot better than about any modern .38, 9mm, .357 or .45 Colt revolver, accuracy wise.
We've done this to a bunch of them, from the 1847 Walker to the 1885 Remington. Great improvement in all of them.