From Open Source Defense:

A sheriff in a rural county couldn’t enforce this law even if they wanted to. 140,000 armed citizens in noncompliance would account for 1.6% of the entire Virginia population. Best estimates of the Syrian civil war show that even at it’s peak, only 1% to 2% of the nation were active combatants, counting all sides. And the noncompliant gun owners have home turf, and are probably better equipped and better marksmen than many of the folks in Syria. The barrier to enforcement isn’t just ideological, it’s functional.