Hello! I’m working on an American Revolution era historical fiction novel for NaNoWriMo. I will likely have more questions, but this is the first one

During the Colonial period, duelling was practically unknown in what would become the United States. A few notable exceptions can be found during those two centuries, most famous being the Philips-Woodbridge affair of 1728, but for the most part the colonials didn't find it necessary to follow the code of duello, and the few duels that did occur involved military officers, or officials recently arrived from the home country.

The initial rising popularity of the duel tied closely to the rising growth of an elite who came to see their identity as less and less tied to the motherland, and it was the Revolutionary generation who were the first Americans to begin to really embrace the institution. Much of the driving force was the sense that the point of honor, and the use of the duel to enforce it, was an essential part of what being a proper military officer was in the period. It was what their British opponents, and their French counterparts, did, so thus is must be what they did too. Resentment of offences and the initiation of an affair of honor, which might or might not then result in a duel, made them feel like proper officers and gentlemen, rather than mere rough provincials undeserving of the label.

The 'craze' among officers of the American Army took off around 1778. some duels and challenges predated it, but Charles Royster convincingly ties it to the time spent at Valley Forge, which is easy to find correlation both with the push to better professionalize the force, as well as the long period of time it represented for remaining in close proximity and on each others nerves. Dueling of course was illegal, and it was regulated within the Articles of War, adopted essentially wholesale from the British regulations, forbidding the sending of challenges, and also the harranging of an officer who refused one. As with the British though, it was hardly adequate as an officer nevertheless felt quite compelled to stand up for their honor. Captain MacNamara's defense at trial a few decades later is by far the best encapsulation here:

Gentlemen, I am a captain in the British navy. My character you can only hear from others; but to maintain my character and station, I must be respected. When called upon to lead others into honorable danger, I must not be supposed to be a man who had sought safety by submitting to what custom has taught others to consider as a disgrace. I am not presuming to urge anything against the laws of God or of this land. I know that, in the eye of religion and reason, obedience to the law, though against the general feelings of the world, is the first duty, and ought to be the rule of action. But in putting a construction upon my motives, so as to ascertain the quality of my actions, you will make allowances for my situation. It is impossible to define in terms the proper feelings of a gentleman; but their existence have supported this happy country many ages, and she might perish if they were lost. Gentlemen, I will detain you no longer; I will bring before you many honorable persons who will speak what they know of me in my profession, and in private life, which will the better enable you to judge whether what I have offered in my defence may safely be received by you as truth. Gentlemen, I submit myself entirely to your judgment. I hope to obtain my liberty through your verdict; and to employ it with honor in the defence of the liberties of my country.

To return to the Americans though, whatever the prohibition, it didn't stop the development of a dueling ethic, which was embraced by many, such as in a letter from Edward Rutledge when he wrote about the Continental Congress adopting the Articles of War:

I proposed to strike out that Article which prevents the sending of challenges, and pressed it as a measure that would tend to make their officers Gentlemen, or at least induce them to act as such whilst in Company with Gentlemen.

His wish essentially came true, not that duelling became allowed, but it certainly became common by the end of the decade, with references to encounters, either explicit or implied, peppered throughout letters and diaries of the time. The French Minister wrote home that by 1779, "the rage for duelling here has reached an incredible and scandalous point". As would be reflected in the enduring zones of popularity, dueling was more popular with officers from the southern colonies as compared to the New England region, although it was hardly a black and white distinction. Benedict Arnold for instance offered a challenge in 1776 - ahead of the curve - when he was brought before a court martial, although it was not accepted.

As for the manner in which these encounters happened, there are two broad notes to be made. The first is to understand just what a duel was, or rather what it wasn't. The duel didn't exist in a vacuum, where one man offended another, a challenge was sent, and they soon faced off at 10 paces. Rather the duel was only one possible conclusion of an affair of honor, which was a process designed to avoid such an encounter. Numbers are impossible to find in a quantitative sense, but many commentators of the period remarked that 9 in 10 affairs never ended up seeing the principals facing off on the dueling field. After cause for offense was given, a process of negotiation between appointed representatives, the Seconds, was intended to prevent the duel from happening, by finding a way to negate the offense, or grounds on which an apology could be agreeable offered. Only if at a true impasse would a duel now be in the makings, with the Seconds now negotiating the terms on which the duel would be fought.

The 1777 code you reference, or 'Irish Code Duello' might, or might not be explicitly used, but it would be generally reflective of the broad framework in which the duel would be arranged, as it was not written from nothing, but rather reflected a codification of practices that were already well known within elite circles and passed along more informally. Other codes would follow it, many quite similar, reflecting this same matter, but in any case, the various codes were less hard and fast rules than guidelines, as in the end the Seconds would negotiate the terms of the duel, including the distance to be fought at, the arms to be used (almost always pistols), time, place, and so on. The regulation of shooting was of key importance, and often reflective of the offense, as a more serious one might see firing done in turns as compared to a less serious one with firing done together (more on the technical things can be found here).

A number of duels from the period of various note can be found and would likely provide examples to use, including the Cadwallader-Conway encounter of 1783, the 1778 Howe-Gadsden duel of which I've written here, or of course the Laurens-Lee encounter also in 1778, of which Hamilton provided an decent account of. Washington himself was critical of the dueling ethic, but his disagreement had not all that much impact, and several acolytes of his fought duels that were essentially on his behalf, defending points of honor that had been made to besmirch their commander. Many of these didn't quite follow the 1777 Code, but would have been broadly recognizable as a proper duel, and also conducted in ways that the authors of that specific code would have approved of, as at the core the important factor was simply the honorable conduct of all parties (see here for more on that).

Sources

I maintain an extensive bibliography, which you can find here, and would particularly point out Greene and Royster as most relevant for you.