In answer to this very question a while back, I looked through history and found something very important:
At no time since the advent of what we would consider "modern" military power -- that is, in the years since the advent of military aviation and mechanized warfare -- has it been possible for an armed civilian uprising to prevail against its government without the support of the country's military.
That's not to say that revolutions don't happen, or that governments don't get overthrown, or that popular revolts cannot prevail. It is simply that a popular revolt cannot prevail unless it is popular with the state's armed forces as well. This, is necessarily, requires a mutiny on a massive scale, usually involving one or more popular generals defecting to the side of the revolutionaries and taking a huge chunk of the army with him.
Once the military switches sides, THAT'S when things become interesting.
The example that really solidified this is the Syrian Civil War. A lot of people forget that Syria has had small scale uprisings before, most of which were quickly and decisively crushed by the Assad government before their feet even hit the ground. But this case was different: some portion of the Syrian military had already joined the uprising earlier in the spring, and by September the Free Syrian Army basically had a core group made up of military deserters and Islamist militia veterans.
To compare with America's situation: imagine if two of the top ranking generals of the U.S. Marine Corps threw their support behind Black Lives Matter and encouraged every black soldier under their command to do the same. In a single day, five thousand soldiers abscond from their bases with fifty trucks, eighty Humvees, twenty M1A3 main battle tanks, and clean out the armories of their bases, including an impressive number of anti-tank and anti-aircraft missiles. When three days later a black teenager is shot in the face while sitting on a swingset in a public park (the officer claims he "reached for his waistband" but no weapon is found), suddenly BLM shows up in the middle of the I-90 with a pair of tanks, a hundred trained Marines with assault rifles and anti-aircraft missiles and announces, "The Kennedy Expressway will remain closed until Officer Dickface is fired and prosecuted for murder."
A responsible government will try to defuse the situation and eventually appeal to the soldiers' sense of honor and get them to turn themselves in to face charges for mutiny, with a dishonorable discharge and a brief jail sentence. An asshole totalitarian government will send another group of soldiers to try and force the protesting soldiers to surrender, which results in two different units of your armed forces opening fire on each other, which in turn results in more defections ("What kind of asshole orders us to fire on our own people just because so Officer Dickface can keep his job? Fuck that!") and makes the revolt stronger.
tl;dr: Any popular uprising against the government is dead on arrival unless at least SOME of the military is backing it up. It is indeed true that freedom grows out of the barrel of a gun, but it is also true that those kinds of guns cannot be bought in stores.
