Duelling with firearms grew in popularity in the 18th century, especially with the adoption of the Irish Code Duello, "adopted at the Clonmel Summer Assizes in 1777 for the government of duellists by the gentlemen of County Tipperary, County Galway, County Mayo, County Sligo and County Roscommon, and prescribed for general adoption throughout Ireland." This proved especially popular in America.
Typical weapons were cased duelling pistols, tuned for identical appearance, reliability and accuracy. In America, the Irish code eventually supplanted the usual method of brutal hand-to-hand combat and gave the combat a respectable feel. However, since the combatants could not control guns as precisely as swords, gun duels had a greater chance of being fatal.
Some duels miscarried because both opponents did not hear or see the starting signal. Agreeing to a signal was helpful.
A custom had grown, before the Irish code, of deloping, discharging one's firearm in the air (usually to one side) when two friends had quarrelled and one (or both) wished to end the duel without harming his friend or appearing cowardly. Far too often, this custom resulted in accidents and the Irish Duello forbade it.
