If the army come after you no amount of arms will save you because they have more and they’re better trained. But if you have a defensible position, enough food and ammunition a small armed group can absolutely hold off another small armed group or a much larger worse armed one. Most of these people are no doubt basically LARPing in their heads. See the Koreans during the LA riots. Even against the state a small group can hold out for a relatively long time. See Waco. It took tanks to breach their defenses.