First, what is the 2nd Amendment?
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.
Basically, we get to have guns, but not unlimited access to guns. The Supreme Court in 2008 puts it like this (via District of Columbia v. Heller)…
The Second Amendment protects an individual right to possess a firearm … for traditionally lawful purposes, such as self-defense within the home. … Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose…
So if you're a law abiding citizen, you can own firearms for lawful purposes: hunting, self-defense, and sport. Currently, "warring with the National Army because I don't like the government" isn't a protected right.
So what is gun control? Maybe you already know. If you're a gun enthusiast, you might say it's proper sight alignment and sight picture, or the slippery slope toward a total gun ban. If you're reeling from one of our nation's bi-monthly mass shooting, you might have a foggier idea about what it really is. It all starts with the 2nd Amendment, which has consistently been interpreted to mean that citizens have the right to own firearms (most recently by the Supreme Court in 2008 via District of Columbia v. Heller), but not without some restrictions.
First, the Bureau of Alcohol, Tobacco and Firearms, or ATF, dictates what's legal and what's not. So owning a 9mm revolver for home defense and sport, legal. Owning a 12 pack of hand grenades, not legal. The automatic Colt M16 combat rifle released in 1960 _not legal, _the semi-automatic Colt AR-15 released 3 years later legal. The government is also allowed to deny ownership of guns to categories of people, mainly felons, people with mental illnesses, illegal immigrants and veterans with a dishonorable discharge. So if you commit a gun crime or have a history of psychiatric conditions, for public safety, the FBI will not approve your background check for gun ownership.
In short, gun control is how the government tries to make sure guns are used lawfully, and not for committing crimes. It's keeping guns from the "bad guys" and balancing rights with public safety (hence keeping belt-fed guns and bombs out of general public use).
Where criminals get their guns
So where does the problem of keeping guns from the "bad guys" start? First off, let's omit good guys who go bad – lawful gun owners with no history of violence that decide to commit crimes. Sadly, many mass shooters fall into this bucket, which is why they're often a red herring in the gun control debate.
Let's assume you're a "bad guy" – someone with intent to commit a crime, and you have a criminal record. You need to get a gun, and here are your options.
Buying from a gun dealer
The first place guns are sold is through gun dealers that are issued a Federal Firearms License (FFL) by the ATF. This is referred to as the primary gun market, and makes up about 60% of gun sales. Right now there's over 140,000 FFL gun dealers in the U.S., and only 1000 ATF agents to enforce regulations. If 140,000 sounds like a lot, many operate without storefronts, often from private homes or even on the road. At best, a dealer may be inspected once a year, so some skirt regulations altogether, skip background checks and even traffic guns to Mexican cartels (where demand is huge). These dealers can often be black market dealers with a legitimate license and really bad bookkeeping.
Assuming you're at a legitimate gun store, and since it's post 1998, you'll have to pass an instant FBI background check. Nowadays this often takes less than 5 minutes. If you pass, your gun's serial number and your info is written on paper, mailed to the ATF, and stored on microfiche. Why microfiche? Because the 1986 Firearms Owners' Protection Act (aka FOPA) prohibits any national gun registry, so the ATF gets by with 19th century technology. In the event you somehow pass this check and commit a crime, if law enforcement finds your weapon, they'll make an often futile attempt to trace you through the ATF microfiche system.
To see how futile this is, try hastily writing down your vehicle's VIN number and ask someone else to read it.
…through a friend
But, likely, with a criminal record you'll fail the background check. No matter – FOPA also requires the FBI to destroy any evidence of your failed background check within 24 hours. No authorities alerted, no record to be used against you in court. If you're still really intent on getting the gun at that store, you'll simply need to conduct a "straw purchase" – you just give money to someone else who buys the gun for you. You could be the next serial gunman, but at worst your straw purchasing friend may face a misdemeanor (see 2014 Abramski v. United States).
…through a guy on the Internet
If you don't find an accommodating FFL dealer, what you'll likely do is buy your gun from a private seller, also known as the secondary gun market (accounts for 40% of gun sales). You can try Armslist, the "Craigslist for guns", or a number of local papers to find folks who grow tired of their revolvers, pistols, shotguns and rifles. Unless you're buying or selling a special category weapon (submachine guns, explosives, and special long barrel weapons), the ATF doesn't govern your transaction. Some states require you to do your gun sale through a FFL gun dealer who performs a background check, but it's so few that you're guaranteed the next state over does not.
…through a "gun enthusiast"
If you don't like what you're seeing in the private listings, you can always go to a gun show. There, while you'll find many normal FFL gun dealers, you'll also find private sellers who use the ATF's vague language for what constitutes a gun dealer and claim to be "casual enthusiasts". As such, they bypass all FFL gun dealer laws – no background checks, no registration. If, say, you live in New York where high-capacity magazines aren't available, well come down to Tennessee and grab a 33 round magazine for your Glock. The only law casual dealers must follow is they cannot knowingly sell to a felon. And as long as your criminal history doesn't come up in conversation, they won't ask.
The sad reality is…
We don't have effective gun laws. Gun rights supporters have fervently fought so hard to keep firearms free of regulation and easy to purchase that there's almost no accountability, tracking or barrier to criminal gun sales. In the few places where gun regulations could work, there's so little oversight that corrupt gun dealers flourish and feed a thriving black market for firearms. In the end, the U.S. has almost half the world's civilian-owned firearms and 2-4 times more gun deaths than any European or Asian country (Montenegro comes close, but it's still recovering from civil war). Uruguay, Barbados, Chile, and Peru all have fewer gun homicides than the U.S., while being significantly poorer and with much weaker police enforcement infrastructures.
I'm a former Marine with two pistols, a rifle and a Concealed Carry Permit. I whole-heartedly embrace a citizen's lawful ownership and use of firearms, but the landscape of gun and ammo sales in America is recklessly tilted toward ease of sale over public safety and crime prevention. While the NRA may drum up a great debate using fears that have no basis in public opinion or reality, it profits entirely from the controversy it instigates and the gun manufacturers that support it, acting as a PR firm for reckless gun marketing and fear mongering.
Americans will always have gun ownership, but we could do much more to ensure that ownership is kept safe, lawful and responsible. A public that doesn't feel safe will always move to the fringes, but avoiding gun violence only helps bolster the rights we agreed to at the dawn of our nation.