Hello everyone, just dropping by to make a quick first post. If you google for "fastest revolver shots" or something along those lines you can find plenty of videos of people using single, and double, action revolvers to fire 6 - 8 shots in under a second. Furthermore, you can also see videos of people using speed loaders to reload a revolver and fire ANOTHER 6/8 rounds all within 2-3 seconds. [That is not a typo or hyperbole btw]
I do not think using Feruchemical steel (or compounding it) does anything to speed up a gun and, as the videos you can search for show, it is entirely possible to use a revolver to fire rapidly without any enhancement to the gun or the individual. I hope this dispells some of the confusion surrounding the opening scene of SoS.