"Six for sure", my posterior.
Revolvers can fail to fire just as much as an automatic. They can have timing issues, mainspring issues, wear issues (i.e., not indexing the cylinder properly), and my personal favorite, failure to be able to reload because your ejector rod unscrewed while you were shooting and you can't get the cylinder open.
How about a personal favorite, getting grit stuck under the extractor star, causing the cylinder to bind?
They never should'a stopped making swords.
[like these...and they laughed when I asked for a bayonet lug..!]