The United States truly is a federal republic. Some very important aspects of life are governed by state law, not federal law, and sometimes they vary hugely from state to state. Firearms law is one of them. The culture with respect to guns varies enormously from state to state. I've never seen guns for sale in a "supermarket," but in Wisconsin I certainly have seen them for sale in Walmart (chain of giant department stores) and many Walmarts have what is practically a supermarket in them, too. In my state firearms are tightly regulated. There are city laws, too. For example it is harder to own a gun or get a license in New York City than in the rest of New York State. And it depends on the type of gun. It is relatively easy to get a single-shot 0.22 rifle in most states; a handgun is harder; and an automatic assault rifle harder yet. I don't own a gun and I don't think many of my neighbors do. I think the Constitution of the United States is one of the greatest works of humankind but frankly they didn't do a good job on the Second Amendment. It says "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." This just isn't clear and lawyers have been fighting about what it means forever. Maybe it means every citizen has the right to carry a handgun. Maybe it means only that a state has the right to organize a state militia. Maybe it means citizens of slaveholding states had the right to organize armed patrols to chase runaway slaves. Maybe not. Everyone says they know, nobody knows.

Hehe. Buy guns in a supermarket? I wonder if that is allowed in Texas. LOL Sorry, no offense to anyone from Texas. :P Anyhow, it depends on the state that you live in. In my state, Massachusetts, you have to have a permit to buy or carry a gun on you. So if you go to Walmart, they will ask to see your gun permit before they sell you ammo or a gun. I have never heard of guns being sold at a supermarket though. That's a little insane, in my opinion. Hahahaha. This Wikipedia article outlines the gun laws for each state http://en.wikipedia.org/wiki/Gun_laws_in_the_United_States_by_state

I'm not really an expert, but I know a thing or two about the subject. A lot of things related to handgun possession differ from state to state. If I remember correctly, there are more states where the minimum is 18 and not 21. It is not the case that most supermarkets carry ammunition, but you would certainly be able to find ammunition at stores like Wal-Mart which are ubiquitous. As for carrying them around, there are different laws concerning "Open carry" or carrying the gun in a manner in which people can see it holstered, and "Concealed Carry" which often requires a special permit. Private business owners are able to specify that they do not want guns in their establishments in most, if not all, places so it can be an inconvenience to be a citizen carrying a gun. One does see it, but it is extremely unusual where I live. The chance of seeing a person with a gun differs greatly from state to state.

I am never afraid. The only person that I know who isn't a cop and carries a gun in my state is my uncle. Hahaha. Perhaps people from other countries have this false image of everyone carrying guns here. Hehehe.

The laws do vary state by state. In my state (Missouri) you need a permit to carry a hand gun, but other types of guns I don't think you need a permit. And you need to be at least 18 to purchase a gun. At my high school there was actually a class where I learned to load and fire rifles (but they were non working guns so no one would get hurt). People's opinions on guns vary. Some people love them, some people hate them, while others don't care either way. It can be scary if you hear a gun go off in a residential neighborhood, which has happened to me only 2 or 3 times. Usually people only shoot guns at a gun range or in a rural area. I've never seen anyone carry a gun around while shopping personally. I hope that answered your question!