More realistic scenarios, based on historical examples, include:
1. Armed resistance of local or federal authorities/law enforcement (e.g. Battle of Athens, Bundy Standoff)
2. Guerrilla warfare against a superior military force (e.g. Afghanistan)
3. Full civil war between the states (would probably look something like Russia-Ukraine war happening right now)
In the first two scenarios small arms are absolutely effective. In the third scenario, access to more advanced weapons and logistics would be split between the factions (and possibly supplemented by outside forces).
