AR-15s are the most popular rifles in America, and for excellent reasons. They are incredibly versatile, easy on the recoil, and nearly universal in customization options. You can purchase an AR-15 and endlessly modify it. You can build one from scratch, starting with the lower receiver, upper receiver, or the stock if that’s what pleases you.
They’re also reliable, so long as you take care of them, and have incredible range. You can hit a man-sized target at 500 yards with the right adjustments, using nothing more than the open sights.
An AR-15 brings a lot to the table, in terms of customization and versatility, that it’s downright overwhelming at times–even for veterans who know and understand the weapon intimately.
Because of this, it’s a good idea to become familiar with every aspect of the weapon, and to do that, you need a solid guide.
AR15’s – Everything you Need to Know
How does an AR15 Work
One of the things that make the AR-15s so popular is the simplicity in execution. All AR-15 variations use a gas recoil system to eject a spent shell casing and push the BCG (Bolt Carrier Group) back to load the next round in the chamber. There are two types—direct impingement and short stroke piston of which the former is far more common.
Direct Impingement System
When the powder inside the round explodes, propelling the bullet through the barrel, some gas is harnessed and redirected. The redirected gas ejects the brass, along with blowing back the BCG, allowing a second round from the magazine to move up.
When the BCG moves forward again, it catches the edge of the new round, sliding it up and forward, so the round is in the chamber, ready to go. All of this occurs in the brief microsecond after you pull the trigger.
Short Stroke Piston
This system works much like the Direct Impingement System. It still uses a portion of gas captured from the fired round. However, the gas is redirected into a separate cylinder that contains a piston. That piston is used to retract a bolt and rod, rather than the entire BCG.
The gas system in an AR-15 is where most beginners get lost when it comes to building an AR-15. The gas system’s capability is directly associated with the length of the AR-15. If you have a long barrel, it stands to reason that you have to have a long gas system.
Too much gas in a short system that doesn’t match the length of the rifle causes damage to the internal components. Too little will result in failures.
AR-15 Dimensions
It’s difficult to just throw some numbers out there on the dimensions of the AR-15 because the thing is they are highly customizable. Plus, companies manufacture them in a ton of variations. The standard AR-15 that most beginners buy comes with a 16” barrel, and that’s the dimension we will use, with the understanding that AR-15s are not one-size-fits-all weapons.
How long is an AR-15
- The length of a standard AR-15 is 32.75”
- The height of a standard AR-15 is 8.75”, including the magazine
- If it comes with a scope, you can add 3” to 4” to the height
- Collapsible stocks change the length
If you’ve only owned one AR-15 and it happens to not conform to the dimensions of a basic AR-15, you might be puzzled by the above dimensions. Think of it as a generalization based on a basic model.
How much does an AR-15 weigh
Like the dimensions of an AR-15, there are a lot of variables to consider, excluding the AR-15 itself, which comes in a variety of weights depending on the manufacturer, capabilities, etc. An AR-15 pistol won’t weigh the same as a standard AR-15.
Standard AR-15s weigh between 6 and 7 pounds, depending on a few factors. The more you customize it, the more you pack on the pounds. An Armalite AR-15 weighs 6.55lbs unloaded, according to the manufacturer.
What caliber is an AR-15
Typical AR-15s come chambered in either .223 Remington or the 5.56. Some AR-15s are interchangeable, meaning you can safely fire either .223 or 5.56. However, if an AR-15 is labeled for .223, you should never fire 5.56 with it since 5.56 is a little more powerful.
6.5 Grendel
AR-15s sold as a 6.5 Grendel are chambered with .264 rounds that pack a little more powder behind them. These rounds are much more suitable for deer hunting. It’s not going to blow your socks off in terms of raw power but it’s suitable for those who prefer a little more kick.
It’s also a toned-down but superior version of the 7.62 NATO, with better range, flatter flight path, and better penetration.
7.62 NATO
The AK-47 isn’t alone anymore. Some of the earlier versions of AR-15s that fired 7.62 didn’t work out so well, but today, there are a few options out there. The range is certainly affected, putting the AR more on par with the capabilities of the AK but you can expect decent accuracy at 300 yards.
It’s good for deer hunting in the woods rather than out in the open where long-range becomes a factor. Plus, a 7.62 round has more punching power in a thick brush.
There are a few additional options but they mostly come from DIY projects rather than on the market. That’s not to say you can’t find them on the market, just that they are more popular with personal builds.
- 9mm
- .22 LR
- 8 SPC
- .300 Blackout
- .224 Valkyrie
- .458 SOCOM
- .50 Beowulf
How to hold an AR-15
Holding an AR-15 the right way takes a bit of practice but it’s important to get it down right and make it a part of your muscle memory. Your dominant shooting hand will always correlate with your dominant eye, even if you are ambidextrous.
An AR-15 doesn’t have much in the way of recoil. Tuck the butt of the stock into the hollow of your shoulder, where your pectoral muscle meets the forward part of your shoulder muscle.
Grip the pistol grip in the webbing between your thumb and index finger. Wrap your fingers around while leaving your index straight and off the trigger. Hold the weight of your rifle with the palm grip, not with your fingers.
Your feet should be shoulder length apart with your non-dominant foot slightly forward of your dominant foot. Keep your nose down and form a solid cheek weld with the stock. It should mush up under your cheekbone.
Your non-dominant hand should form a V-grip on the handguard or a standard grip but far out on the handguard, not close to your dominant hand. Lean in a bit and keep your shoulders square.
How far can an AR-15 shoot
That depends on the caliber, the makeup of the AR-15, and the shooter. A 5.56/.223, in a standard AR-15, has a range of anywhere between 450 and 650 yards.
An AR-15 pistol lacks the range of an AR-15 with a 16” barrel. But there are some general estimates based on caliber.
- 9mm – 100 to 150 yards
- .450 Bushmaster – 250 to 350 yards
- .308 – 700 to 1,000 yards
- .50 Beowulf – One mile
- .338 – 1,000 yards to One Mile
With all things being equal, that’s generally what you will get from those calibers.
How to remove an AR-15 Stock
After clearing your weapon and placing it on safe, separate the upper receiver from the stock by removing the pin just behind the safety catch. 
The upper receiver will angle forward on the remaining pin, like a hinge.
You’ll need an AR Armorer’s Tool to remove the locking ring at the very front of the stock, close to where the upper receiver separates. There is a pin and spring locking mechanism that will pop loose while you are unscrewing the locking ring. If you can locate it before you start, put a finger on it so it doesn’t spring loose and go rolling off somewhere.
In most modern AR-15 styles, this will drop the entire stock off the back. However, some stocks will have an additional screw located in the butt of the stock. It tightens the stock to the extension tube. Simply place the new tube on and screw the locking ring on, then tighten the butt screw to tighten the stock.
Cleaning an AR-15
Cleaning your AR-15 is every bit as important as how you treat it in the field. The reliability of your rifle should be beyond question. If you don’t have complete faith in your AR-15, you shouldn’t fire it, especially hunting.
Fortunately, an AR-15 is pretty simple to disassemble. You’ll also need a gun cleaning kit with a bore brush that matches your caliber. Be sure to clear the AR first. Release the magazine and clear the chamber.
- Flip the safety on
- Separate the upper and lower receiver by removing the pins located in the front of the magazine and one just behind the safety
- Remove the BCG by drawing back the charging handle and pulling the BCG with it
- Use a pick to remove the retaining pin
- Remove the firing pin from inside the BCG
- Rotate the cam pin and remove it
- Remove the bolt
- Use a punch and a mallet to remove the extractor pin from the bolt
- Remove the extractor
- Remove the buffer and spring from the buffer tube
Clean the chamber and the barrel with your barrel brush, and be sure to do it from the rear to the front. Feel free to get creative and work your brush through all of the hard-to-reach areas. Use a wire brush to scrub the BCG and the disassembled parts from it.
Use white rifle cleaning rags to go over every inch until no more carbon comes off on the white rags. Use a lightly oiled rag to clean the charging handle and upper receiver. You don’t need to get crazy with it–just a solid wipe-down. You can use CLP for the toughest areas but don’t make the mistake of overusing it. For the light oiling parts, just stick with lubricating oil.
The same goes with the buffer assembly, nothing more than a little light oil and a rag. The fire control group and the lower receiver take a little more time. Use a wire brush to work in and around the moving parts as much as you can. Then rub everything down with a lightly oiled rag.
Where to oil an AR-15
This is where beginners go a little crazy with the oil. There’s no need for that. All you need is a light coat of oil on a few, crucial components inside and outside your AR-15.
- Fire control group
- All the components of your BCG
- Charging handle; top and bottom but not the wing at the end
- Bolt catch button
- Mag release button
- Safety selector
- Anything else that moves
All you need is enough to leave a light sheen on everything. At no point should anything drip oil when you are reassembling the rifle.
Where to lube an AR-15
Gun oil is your lubricant. A lot of people like to use the terms interchangeably and some consider them to be two different things. 
The only differences here are the CLP and Hoppe’s No. 9 Lubricating Oil.
CLP is more of cleaner and you will use it for the areas that are the heaviest in carbon deposits. However, you want to remove as much of the CLP as possible and wipe those areas down with light lubricating oil.
Every other moving part should have a light sheen of lubricating oil on it. Don’t get caught thinking that you need to douse the rifle in CLP. That’s not the best idea as CLP can cause damage over time. Simply use the CLP to clean and the lubricating oil to lubricate and maintain.
Bottom Line
The AR-15 is not likely to lose its “king of the rifles” status anytime soon. Due to their high level of customization and the myriad options in caliber, sizes, and function, there’s just too much to like for the AR-15 to fade away into history.
It’s not the greatest weapon in the world, of course, but it is a fantastic addition to your home defense needs, competitive shooting, or even a dependable hunting rifle.
Visit the OutdoorWorld Reviews homepage for more expert information and reviews of AR15 accessories including slings, bipods, cases, lasers and scopes.
