I have 2 reproduction cap and ball revolvers, 3rd Model Colt's Dragoon and a Colt 1861 Navy (mechanically almost identical to the 1851, but with the smoothed off lines and round barrel, like a slightly smaller 1860 Army) - both Uberti replicas.
Both of them have nodules/raised bumps on the cylinders in between the caps, which are supposed to engage with a notch on the hammer, to lock the cylinder in place and prevent the hammer resting on a cap. However, all of the ones on the Navy and most on the Dragoon have worn so much that they don't work, and you can rotate the cylinder by hand. I think the trouble is that the cylinder is made of mild steel, and the bumps are only small, and get worn away easily when engaging with the hardened steel hammer.
If I was carrying either of mine in a holster going about my day to day business, I would only load 5.