History proves time and time again......
A well armed society has a "well behaved" government...and when it misbehaves, those armed citizens can do their job
The "Point" of an AR-15 is to give the citizens some chance against tyrannical forces that may be better equipped, but would be hopelessly and vastly outnumbered. Remember that the US' superior capabilities still didn't prevail against a far lesser enemy in Vietnam and other conflicts.
Now given that government troops would be killing their own citizens on their own home land, the probability of collateral damage in terms of also killing government friendly citizens makes their task many times more difficult than Vietnam etc.
IF (a big if) enough American citizens decided enough is enough and were willing to defend their liberty, the government would have a hell of a hard time stopping them. Far harder than you might think. Factor in that many with access to advanced military weapons and vehicles might use them against the government.
Also, factor in China and Russia would likely use that time to attack targets that America has sworn to defend forcing military assets to be used overseas and against foreign attackers at the same time. I personally do not believe the government could pull it off and would be fractured to the point of being easily dismantled by Patriots at that point. Their ONLY chance government has is tricking citizens into willingly give up their arms through threats like taking away things and threats of prosecution. And that is precisely what the government is doing right now.
The US is entering a stage where government has become corrupted and tyrannical.
The most significant sign of this is it's current hard core push to disarm the citizens.
Right now, today is by far the most critical time in American history since 1776 that Americans must not give up their AR-15's or any weapons to government threats.