Doesn’t seem to terribly difficult if you’re going to stop when, “Goddam, we hurt somebody!”
I admit that the lack of antibiotics and the usual treatment of being bled would make it more dangerous.
But then you’d have proved that you weren’t a gentleman… or as a friend of mine once put it:
“Of course the challenged party can choose any weapon, but should he select something other than a rapier or sabre then he has demonstrated that he is no gentleman and the correct response is to send ones groomsmen to horsewhip the cur on the steps of whichever club has the poor taste to entertain him as a member”. 
Good Gad, Sir, that is outstanding! A veritable Flashman decision, far better than my brickbats at half a mile.
IIRC, there were some duels where the duelists fired in turn, and others where they fired more or less simultaneously.
In the former cases, who gets the first shot?
A smite from Schläger duels,
CMC fnord!
Of course, one way to win a duel was to be a smartass. Abraham Lincoln was challenged to a duel following a letter his wife published in the paper; he accepted, chosing cavalry broadswords as weapons. His opponent showed up, saw this humongous farm boy carrying a 3-foot meat cleaver, realized that no skill at arms would get him out alive, and called the whole thing off.
Depends on the region, but I believe the challenger (as the offended party) got the first shot if those were the rules being used (Generally both parties would fire simultaneously, though).
You could choose not to fire simultaneously, though. I remember reading an account of Andrew Jackson where he allowed the other guy to fire first, took the hit, then carefully and methodically raised his own pistol, to careful aim and put a ball into the chest of his opponent. He nearly bled to death afterward, but I don’t recall anyone else being foolish enough to prompt another duel from him after that. Anyone who is that cold blooded…well, best to just leave them alone, I’d say. :eek:
-XT
I used to jokingly respond to friendly insults by suggesting a duel with swords at twenty paces. It’s amazing how many people would actually point out that it was impossible to do any damage that way. Although one person did speculate on whether he could throw a sword that distance with any accuracy.
Wasn’t there some flexibility about the number of paces, and the more you chose, the more it showed that you were just looking for the ritual and not seriously intent on killing the other guy?
Also, I’ve forgotten; there was a duel in one of the early Hornblower novels between Hornblower and another officer, and
the captain did not want two of his officers dueling, so he somehow had the seconds sabotage the duel. Did they substitute blank rounds?
As my copy of Mr. Midshipman Hornblower happens to be handy -
[spoiler]Hornblower was accused of cheating at cards by Simpson, another midshipman, and after being refused an apology challenged Simpson to a duel. After some discussion with his seconds about the best choice of weapons, Hornblower proposed that they use pistols, one loaded and one unloaded, to be selected randomly, at a distance of one yard.
At the duel, Simpson placed his gun against Hornblower’s chest, while Hornblower placed his to Simpson’s shoulder. When the order to “fire as you will” was given, Hornblower pulled the trigger; his weapon was unloaded, but when Simpson fired a second later his apparently misfired. The Captain later admitted, upon being asked in private by Hornblower, that he had ordered that both guns be unloaded, so that he would not lose a good officer but their honor would still be satisfied.[/spoiler]
Flashman deloped in his duel but he shaded the odds first; I had hoped someone would call old Flashy up.
I think something similar is recounted in War and Peace
But the guy who waited, taking the hit, and then slowly and carefully shot… missed. 
The Love and Death version remains the gold standard.
Having watched the same show that the OP presumedly did (it was this week’s episode of Castle - still available for viewing on Hulu) I was wondering the same point. Sure the two duellists may have been safe from each other because the guns had no accuracy. But they were firing guns off in the middle of Manhattan.
A lot of people seem to believe that any bullet that misses its target then safely evaporates in mid-air.
It was in 1842 and the opponent was the Illinois state auditor, James Shield. The dispute was over the State’s refusal to accept its own warrants and notes (paper money issued by the state treasury) in payment of state taxes. Shield challenged Lincoln over a mocking letter to the editor As the challenged party Lincoln had the choice of weapons. As you said, Abe chose cavalry broadswords – affectionately know to the troops as the old wrist breaker – with murderous long and heavy blades.
One story is that Shield was hot for the fight until, as they waited for the seconds to arrange things, he watched the six-foot-four and extraordinarily long armed Lincoln idly using his saber to chop at twigs on trees fully twelve feet above the ground. That sight gave Shield a clearer understanding of the dispute and a settlement was quickly reached.
I misread Shield’s title as the Illinois State Adulturer, and wondered why he didn’t duel more often.
He obviously had better things to do with his time.