Most gun control arguments have no factual basis.
1. Saying the Second Amendment 'was written in the era of muskets' and therefore doesn't apply to a modern day USA is stupid, because there actually already were semi-automatic rifles at the time the constitution was drafted (Girandoni Air Rifle).
2. Even if you were able to somehow circumvent the Second Amendment and completely ban guns, how do you expect the police force to effectively confiscate over 3 million firearms across a 3,500,000 square mile landmass? You could try a buyback program, but in Australia only about 20% of the firearms ever got turned in through it.
3. Banning guns does not mean citizens and criminals suddenly forgot how firearms work. If German prisoners can make a working zip gun with stuff they found in their prison cell, and Brazilian favela gangs can make semi-auto .50 caliber rifles with basic machining, imagine what a criminal could make in his garage in the US.
4. If more guns = more crime, how come Vermont, a state which has some of the most lax gun laws in the union, is the second least violent state while the District of Columbia, with very heavy gun control measures, is the most?
5. While they are most definitely horrific, mass shootings are simply not as big of an issue as the media makes it out to be. The United States' violence rate does not come from public mass shootings, in fact, deaths from mass shootings make up less than 1 percent of people being killed in the US yearly. The real issue is inner city violence, which gun control advocates simply don't mention because they know that more gun control measures would not stem it.
6. If gun control would lower violence, how come mass shootings are happening almost hourly in Europe right now?
and lastly:
7. SHALL
NOT
BE
INFRINGED
Guns should be taken away from people who do not meet the mental qualifications that would be put in place. If you think anyone with any type of violent mental disability should be able to own a gun, then I feel very sorry for you.
Stop listening to the NRA. They are lying to you.
The NRA does not advocate for mentally ill people to get guns. In fact, they were a primary force in getting the Federal Background Check instituted in the first place.