Concerning chain fires, have seen such happen. One, fired two adjoining cylinders, shot the barrel wedge out and bent the arbor. End of one Colt Navy. The other, was probably an unsealed chamber, as this was at a 'historical' reenactment in Colorado. No ball loaded, but did crossfire the cylinder. In reference to Civil war incidents, there is a triomphe le oil painting (still life) which shows a Colt Navy picked up on the Gettysburg battle site. Two of the cylinders had been damaged. Also might consider that, in military use some did have extra preloaded cylinders. So these would have been very carefully loaded prior to a fight. And also, insofar as infantry units, usually the officers had the pistols. And being line officers, their main focus was keeping the unit in control...so their pistols were not used that much.
In a civilian context, in the towns...it wasn't uncommon for pistol owners to pay gunsmiths and etc, to carefully load revolvers. (Mentioned in some California Rush journals). That would have reduced the likelyhood of chain fires