This is exactly what happened during the civil war. Union army was reluctant and refused to engage in combat, letting Confederate forces withdraw instead. Some yahoo ambushed a well known Union Officer and killed him to support the confederacy and the gloves came off.
Imagine how quickly knowledge of this sort of incident would spread in todays world vs 1861.
No, you should just dig a large hole in the ground and toss your guns in there and burry them. That's what other countries did and it worked for every single one.
Don't be scared about tyrrany. You already have it in the form of two party system ruled by the homogeneous clique of oligarchs.
As evinced by all the people attacking the military all the time?