I just got my new Pietta 1851 Navy .44 brass-frame Friday )ordered from Midway the 13th, shipped the 15th, and reached me probably Thursday the 18th - shipped USPS), and shot it today. Very nice, totally reliable, and only shoots 7 inches high at 15 yards. My old 1851 Navy (bought in 1976) is quite different in manufacture, and current 1851 parts don't fit it. The cylinder is 1/8" shorter, and the lockwork parts are more delicate. Having broken it many years back, I consigned it to the display wall - but can generally manage to shoot a couple groups before it locks up again. The new one seems more robust, and looks like a close match in receiver and lockwork to my early eighties Pietta 1860 brass-frame .44.
The older guns shoot about 8 inches high, but all three group pretty decently.
The old 1851 shaves a good ring of lead with a .454 ball, but the two newer guns barely shave lead. I think the old one is a Pietta, judging from the frame markings, but am not positive. If so, manufacture was changed at some time.
This new 1851 Navy is on Midway's website, for $89 - their least expensive Cap&Ball, but it isn't shown in their latest catalog - maybe discontinued? A great deal, as it's nearly half the price of the other Piettas.