See, posts like this are why firearms rules are complete nonsense in most D&D-derived works. They're not magic death wands.No. That's precisely what it doesn't handle well.
When you have one or two "shots" per turn at say 5th level that deal 1d6 or 1d8 you're not simulating guns. I don't know what you're simulating, but it isn't bullets. Even a "crit" with a gun is so minimal damage as to make a mockery out of the lethality of firearms.
If you get a bullet in the brain, heart, or lungs you are probably going to die in a matter of seconds. If you get a bullet in the intestines, without medical attention, you are probably going to die within a matter of days. Take a hit anywhere else... well... you're just not going to die at all.
They're a lot like daggers, really.
Main difference between the two is that a non-lethal firearm attack is somewhat more likely to cause permanent, debilitating inuries-- the kind of realistic injuries that the D&D rules deliberately do not model.
There is no point at which D&D's modeling of weapons and injuries even approaches realism. Firearms only appear to be more unrealistic because we are more familiar with their portrayals in the media.