The Girardoni air rifle was a 22-shot, magazine-fed, nearly silent .46 caliber repeating rifle adopted in 1780 by the Austrian Army. Thomas Jefferson purchased two of these rifles, which he sent west with Lewis and Clark.

Does it have a high-capacity magazine? Got it!

Is it capable of firing 22 aimed shots in a minute? Got it!

Is it a military weapon? Got it!

Was it manufactured during the American Revolutionary War? Got it!

While the standard arm of the day was a single-shot flintlock, the Girardoni offered a massive firepower advantage to the men who carried it.

https://www.buckeyefirearms.org/op-ed-thomas-jefferson%E2%80%99s-%E2%80%9Cassault-rifle%E2%80%9D-%E2%80%93-girardoni-air-rifle

More examples of guns other than single shot muskets that existed then -

https://dailycaller.com/2016/06/29/these-guns-dispel-the-notion-the-founding-fathers-could-never-have-imagined-modern-assault-rifles/