The "well-regulated militia" point:
I've personally never found it difficult to see that the intention here is to say that for a militia to exist (which at the time was all able-bodied men of voting age), people had to be able to keep and bear arms, as in small arms (pistols and long guns), which were in common use by the infantryman of the day. But if that isn't enough for you, there are plenty of writings from the founding fathers that make it much clearer that this was always intended to be an individual right and that it was tied to the right to self-defense, which in there minds could potentially include the American government, hence, "the security of the free state."
Inevitably this leads to the "then people should only be limited to muskets," again, this right is tied into what the average infantryman would be using as arms. And just to show how ludicrous this argument is, would you, for example, argue that free speech should be limited to printed media and standing on the side of the road yelling since that was all that was available at the time?
"The government would never turn tyrannical."
It actually arguably has a few times. The Aliens and Sedition Act, executive Order 9066, and of course that whole slavery thing, and the attempted Native genocide thing. More recently there's the Patriot Act and the actions of the NSA which Snowden released. Plus, I know how some of you feel about Trump.
So between stuff like that, all the examples of law enforcement abuse and just a general distrust of government that's been inherited from both sides of my family, I'm not willing to give the government the monopoly on firearms.
"If the government ever turned tyrannical, regular people would never stand a chance."
What, so you want to make sure or something? Hell, some chance is better than no chance. The Vietcong and Iraqi insurgency gave the US military a run for their money, and we're still fighting in Afghanistan. Which, speaking of, the mujahideen gave the Soviet military a run for their money, too. I'd much rather anyone thinking they're going to pull anything in this country have to think about that old saying of "a rifle behind every blade of grass."
So basically this boils down to a liberty vs. security argument, and as has often been attributed to Ben Franklin, "Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." Someone indirectly brought up the Patriot Act as an argument in favor of gun control.
Do I really have to explain why it was wrong to trample on civil liberties in the wake of 9/11, or for the "War on Drugs" for that matter? Does it not occur to you that trampling on civil liberties is always wrong?
"But the victims."
Yes, it is tragic that these people lost their lives, and it always is when someone is killed or harmed through the actions of others. Is it any less tragic if someone is killed on a more personal level than through a mass shooting? Is it less tragic if someone is killed through a complete accident where no harm was intended to begin with? You are never going to convince me that curtailing the rights of everyone because of the actions of a few is the right thing to do in any case, and parading dead bodies in front of me in an attempt to appeal to emotion is frankly disgusting, and has quite the opposite effect on me. I tend to be suspicious in general of people who try to appeal to emotion, especially when it comes to suggesting I give up liberty or accept something the government wants to do "for my own good." That shit is how we got the Patriot Act.