Should I use a rifle for home defense?

There are lots of thoughts on this and some recent trends and testing are changing opinions.  Unlike selecting a gun to carry with you concealed every day, size and weight is not as big of a consideration.  There are other considerations that rise to the forefront however.  One of the big ones is penetration, or specifically over-penetration.

It's relatively common knowledge that in general rifles and shotguns are more powerful than handguns.  This isn't always the case of course, a 44 magnum handgun is more powerful than a 22 rifle.  However, take that 44 magnum cartridge out of the revolver and put it in a rifle and it's going to be more powerful.  Why is that?  When the powder inside a cartridge burns (it burns so fast we perceive it as an explosion) it gives off gas or fumes that create pressure that push the bullet down the barrel.  The longer the barrel, the longer time that bullet has to accelerate and the faster it ends up going by the time it exits the barrel.  If you are interested in seeing some data on this, I recommend the excellent resource Ballistics by the Inch.  They actually measure this effect for different cartridges.  Most of the time a longer barrel means more velocity.  You can get a barrel long enough that it slows down the bullet, but in general a longer barrel equals a faster bullet.

The Marlin 1894 is a popular pistol caliber carbine

 Even common handgun rounds like 9mm or 38 special will be more powerful if they are shot out of a rifle because they will be moving faster when they exit the barrel.  Rifles that are chambered in common pistol calibers (like 9mm and 38 special) are often referred to as "Pistol Caliber Carbines".  These were popular with police departments for a number of years and are also popular with the Cowboy Shooting crowd.  They come in different actions, semi-auto (aka self-loading) and lever actions being the most common.

The Kel-Tec Sub-200 is another popular pistol caliber carbine

Because rifles and shotguns are more powerful than handguns (again, in general) people often assume that their penetration capabilities are superior as well.  That's a reasonable line of thought, but not always true.  It can be true, certain rifle and shotgun rounds offer a lot of penetration, far more than common handguns.  Lots of recent tests have show that there are other factors to consider however.

A lot of tests involve the very common 223 cartridge.  Rifles chambered in 223 have been selling briskly, in face the AR-15 specifically was the top selling model of rifle the last couple of years.  The 223 cartridge is a little bullet with a case that holds a fair bit of powder.  For example a 9mm cartridge has a 115gr bullet that is propelled by 5gr of powder (give or take).  A 223 cartridge has a smaller 55gr bullet propelled by 25gr of powder.  A bullet half the weight with 5x as much propellent means it scoots the bullet along a lot faster than a 9mm.  In fact, with lighter bullets like that 55gr I mentioned in the example, it moves so fast that the bullet fragments or tears itself apart when it hits something solid.  It basically destroys itself on impact.  For lots of details on this phenomenon and when you can expect it to happen, you can read this older article at the ammo oracle. 

A bullet that shreds itself when it hits something solid is a good idea in a home.  If you need to use it against an attacker it reduces the chance the bullet will go right through them and possibly hurt anyone else.  If you miss and hit an interior wall, that's enough of a solid object to start it breaking up as well.  After a couple walls it's decided less lethal.  If you would like to read a test on bullet penetration in a home, this article on Drywall Penetration is a good read.

This is the primary reason you see more people recommending rifles, specifically 223 rifles, for home defense.  This is also why you see more police departments using rifles chambered in 223 instead of pistol caliber rifles or sub-machine guns.  A 9mm fired from a rifle or sub-machine gun can punch through several interior walls and still be moving at a lethal speed.  This can increase the chance of an innocent person getting killed or wounded.

The AR-15 is the most common 223 rifle today

As I've said before, if a person knew they were going to be attacked on any given day and could choose a weapon, it's going to be something like a tank.  Since we can't do that, we must compromise.  In general rifles are more powerful than handguns and thus more likely to stop an attacker.  This is why we see a lot of people recommending 223 rifles today, they offer the advantage of more power over a handgun with no additional danger of over penetration.  In fact, a 223 rifle can offer less penetration than certain handguns.  Many people view it as an ideal choice for home defense.

There are some drawbacks.  A rifle cartridge, even an intermediate-powered cartridge like the 223, is loud indoors.  Like, 1980's Van Halen front row loud.  If you fire it indoors you will likely have ringing ears for a day or longer and may even sustain permanent hearing damage.  The risk exists with handgun cartridges as well, but the more powder a cartridge has, the louder you can expect it to be.  How loud exactly depends on many factors, but a .223 cartridge fired from a 20" barrel is going to generate sound equal to 155db or so.  The National Institute of Occupational Safety and Health suggests anything over 140db can cause hearing damage.

Caliber for caliber, a pistol caliber carbine (a rifle chambered in a pistol caliber) is going to be a bit quieter than a pistol.  A 9mm Glock 17 with a 4.5" barrel is going to be louder than a 9mm Beretta Storm carbine with a 16" barrel even though they fire the same cartridge.  Why is this?  The longer barrel on the rifle means all of the powder can burn before the bullet exits the barrel.  On handguns this isn't always the case which results in more of a blast at the muzzle.  The longer barrel also moves the sound away from your ear, and the farther you are from a loud sound the better.  A rifle chambered in a pistol cartridge like 9mm is going to be quieter than one chambered in a more powerful caliber and quieter than the same cartridge in a handgun.

There are other downsides to using a rifle for defensive purposes.  It is more difficult to hold a rifle in one hand and a flashlight in the other.  This is pretty easy with a handgun.  If you hear a noise at night and want to investigate, it makes sense to walk about with a light in your hand and have your firearm available.  This is harder to do with a rifle than a handgun.  They do make lights that attach to your rifle, but now you have to point your gun at anything you wish to illuminate.  That's probably OK if it's a bad guy.  It's less desireable if it's your kid sleepwalking, your teenager sneaking back into the house or the fire department telling you there is a gas leak on your block.  Remember the rule of firearm safety - "Never point your gun at anything you do not wish to destroy".

So, it's back to the compromise.  You have to find something that works for you, something where you can work with the limitations.  If a rifle falls into that compromise for you and your situation, I think that it's a rational choice.  A rifle in a pistol (9mm, 357 or similar) or intermediate powered caliber (like 223) may be the best choice for your situation.

Whatever you select, do some research on ammunition.  In handguns a load designed for defensive use is a much better choice than the cheap ammo you use at the range.  The cheap ammo uses a bullet with a full metal jacket, meaning the bullet is entirely covered in metal.  These types of bullets don't deform much when they hit barriers and offer a higher chance of over-penetration and hurting or killing an bystander.