I think all of us (that actually shoot K's of rounds per a lifetime) experience either a jam, bad round etc. that results in the need to perhaps 'clear' the weapon which can be done almost instantaneously by a trained shooter. I have found it's always (for me) a result of cheap bulk ammo so I expect it every now and then but I have never had such occur with costly carry ammo.
While not a revolver guy (I actually like them but allocate my funds according to the ammo I have on hand which is 90% semi-auto) I have read more lately of cylinder shell extraction issues' due to bad tolerances' and the like (gun-tests had an article on this) yet I have personally never seen one 'lockup' at the range. In theory this would be a problem if one had to reload for defensive purposes and found he or she had to 'pry' the rounds out.
Point is I think with either platform that "inoperable" failures are an infrequent occurence at best. My Dad (God rest his sole) taught me a long time ago, however, that anything man-made (mechanical) can fail/break at any time--It is precisely for this reasng that I religiously carry a small BUG
--it's so small as though IMO there's no excuse not to.