One gun fetishist I know, of such stature that he writes for gun magazines, is convinced that a .50 BMG rifle will knock an APC over on its side. Another is sure he could “easily” shoot down a police helicopter with his AR-15. Unlike the anti-armor .50, the latter case is at least possible but it’s much more likely he would miss or do minimal damage and either be arrested or shot by the SWAT team the chopper would direct to his lair.