Nothing wrong with certain guns and rifles for hunters and farmers but why do people need ak47's or armour piercing sniper rifles at their house?

The reason people buy AK-47s is because they are the cheapest, most reliable military style carbines available. They are inexpensive to manufacture and are easily manufactured using older machinery unlike more modern polymer frame or alloy frame weapons. 7.62x39 ammo is also the cheapest among centerfire rifle cartridges. 

Military style carbines/rifles are popular for the same reason why military and police use them; they utilize quickly changed magazines that hold 20-30 rounds on average and are designed for quick handling (ie. combat, meaning situations where your target is firing back at you). Naturally, these features are not required or even favorable for sport hunting, or even subsistence hunting despite what anyone would have anyone else believe. They are adequate weapons at best for any type of practical hunting. As far as hunting goes, if it takes you more than one shot, you're doing it poorly. 

"Armour piercing" is a term most often thrown around by people who don't know the difference between regular ball ammo and armour piercing ammo. Armor piercing ammo is rating according to its ability to penetrate armour, as in hardened steel plate, not the normal building materials used in automobiles, windows, houses, whatever.

Unless you're driving around in a military armoured vehicle or wearing military grade Class 4 body armour; armour piercing/non-armour piercing ammo is the same thing. Tungsten carbide or hardened steel carbide (light armour piercing) vs lead core doesn't make a bit of difference. Either bullet is equally lethal. 

"Sniper rifles," another term typically thrown by what NRA types like to call "gun grabbers" are by definition, any highly accurate rifle (typically with optics/scope) with long range capabilities (centerfire cartridge). Even the long range definition can be thrown out as police sharp shooting (hostage situation, armed criminal stand off, etc) is typically done at distances of under 100m. So by that definition, any accurate rifle (meaning any rifle that is well engineered and manufactured to precision standards, or any rifle worth paying decent money for to put it simply) is a "sniper rifle" to which I have to say wrong. No debate; no argument necessary. Any hunting rifle with optics is a "sniper rifle" in the mind of the ignorant or individual pushing an anti-firearm agenda. Indeed, most military and police "sniper rifles" are bolt action rifles, many of which are built upon civilian models originally designed for hunting. 

While I'll be the first to say anyone is entitled to an opinion, even if it's about something they know little or nothing about, in the age of the internet/google/wikipedia, about the only kind of ignorance that is explainable is the type of deliberate ignorance some choose to use to excuse or explain their POVs.

Dude, tear gas doesn't even work on on every person. Anyone who's been exposed to tear gas more than once knows how to respond appropriately to avoid being incapacitated.

As for nerve gas, I don't even think I can have a conversation, much less a legitimate debate with anyone who thinks it's a favorable option to a bullet unless you're trying to indiscriminately take out a large group of people. 

I'm starting to sound like a pedagogue here at the risk of annoying even myself.

No small handguns for personal safety. Any low caliber pocket pistol is better for mugging someone than defending oneself. Personally, I can't stand cheap pistols or any "mouse caliber" pistol supposedly designed for personal defense. 

Unless it's explicitly for precision target shooting at the range, nothing less than 9mm should ever be considered for "safety" or personal defense. And even then diligent training and the accuracy it fosters trumps any caliber you can choose. 

I blame Hollywood. Oh yeah; and video games. 

I kid, but I do remember that the same Desert Eagle .50 AE at the range I used to shoot at that sold for $600, sold for about $1000 after The Matrix. 

As for the AK; they're just plentiful. As far as I know, there have been more AK-47s made than any other firearm in existence. As far as cost, I don't think a more rugged, reliable weapon exists in the same category. Accuracy wise, just about everything in the same range beats it hands down. 

Because of this, they really aren't good for anything but firing a lot of bullets in short order, which is to say they are among the least practical firearms to own (Desert Eagle .50 AE says hello also) for anyone who isn't a criminal or simply unable to afford something more accurate. This is not to say that there aren't high grade AK based models available (Finnish Valmet, Israeli Galil, etc.), but these are not the ones going for $400 on the US black market or being sold for $30 to Sudanese child soldiers. 

So no; maybe not overkill. Just a really curious choice for "home defense" to put it mildly. Besides, only a complete jackass would use a 7.62 rifle for home defense who didn't live out in rural country. Overpenetration in densely populated areas is no laughing matter. 

To the Afghanis living in Afghanistan; hell no. You'd be nuts NOT to own one. 

So yeah; no AK-47, not because it's "overkill," but because it's a poor choice. But if someone wants to buy an AK-47 legally, who am I to criticize their choice?

If someone really wanted to be civic minded about home defense in an urban area they had no choice but to live in; 12 gauge pump action security shotgun, 20" barrel, 8 shot tube, and load it with non-lethal neoprene buckshot if you've got a bleeding heart for criminal types.

00 buckshot if you don't.

Video games have made a lot of certain guns popular and overall young people know way more about them then before. (well mostly about the different types)

I have a cousin who is a gun fan and due to Call of Duty, certain guns especially AA12 shotgun have become incredibly popular.

Also, I am not an anti gun guy and do like going to a gun range once in a while. Most likley, If I lived in the US I would own a gun.

Doesn't the AK-47, in its standard configuration, have an effective range for a single point target of over 400 meters for semi-auto fire? It's not great for a rifle but let's face it, when it comes to home defense I can not imagine the AK-47's accuracy being an issue.

@BasilZero

The average hunting rifle has about double the stopping power of an AK-47 and has an effective range advantage for a point target of about 200 - 400 meters.

You would have to be a pretty excellent shot to accurately engage a man-sized target with an AK-47 at 400 meters. With iron sights, you'd have to be Carlos Hathcock. 

The design itself was never really for true "rifle" ranges. Because the field strip cover is on the rear of the rifle, the rear sight is placed well forward of the magazine well. Paired with a 16" barrel, the short sight radius means harder to aim at longer distances. That's part (as well as lack of shoulder/stock stability) of why pistols in general are difficult to fire accurately at even 100 yards (long range for a pistol, short for a rifle).

To make things worse, the 7.62x39 round is one of the least inherently accurate centerfire rifle rounds ever made. 3-5" MOA through a standard AK-47 for regular ball ammo which is worse than a lot of modern pistols. 

The AK-47 is really best deployed more like a submachine gun than a rifle. A lot of SMGs like the MP5 and UMP are more accurate than the AK. 

Naturally, any firearm will be made easier to hit targets accurately with the aid of optics, but I personally don't see the point of tricking out a base AK-47 chambered in 7.62x39 with good optics unless one was really attached to the model.

But as I said before, there are plenty of AK variants that don't fall into the base category, but once you start comparing high end, custom built, custom chambered and AK derived models, you're pretty much no longer comparing the same rifle. 

If you're shooting in an average sized room, no. Of course even any decent handgun will give you all the accuracy you need.

Of course if you're shooting an AK in an average sized room, I'm assuming you're not actually living within city limits. The only people that should be firing rifle rounds within an American city should be trained SWAT/LEO.