AR-15 Rifles Guide: Everything You Need to Know

AR 15 Complete Guide Graphic
November 9, 2021 Edited March 23, 2023 4649 view(s)
AR-15 Rifles Guide: Everything You Need to Know

If you’re looking for a crash course in everything AR-15, you’ve come to the right place.

Written with the beginner in mind, this is a basic overview of basically everything related to the AR-15. From history to application to political controversy, this is an introduction into… everything.

Sit back, strap in, and let’s dive in!

Eugene Stoner Holding AR-10


History And Development

The history of the AR-15 is pretty cool and several books have been written on the topic. I’ll try to give you a short version though.

Basically, the story really starts with the AR-10 in the mid-1950s. At the time, the USA was looking for a new rifle to replace the M1 Garand.

ArmaLite, a division of Fairchild Aircraft Corporation, had two amazing engineers -- Eugene Stoner and George Sullivan.

Not new to the firearms world but coming with backgrounds in aircraft that brought with it a lot of new ideas, Stoner felt he could make a better rifle than anything that was being tested.

Enter, the AR-10 rifle. This was a revolutionary design that was lightweight (compared to the other rifles in the trials), easy to shoot, and with unbeatable reliability.

Sadly, the trials didn’t go well. Due to a bad decision, the AR-10 failed the trials and was removed from consideration.

But the seed of an idea was there. Something that would quickly grow into the AR-15.

Soon after those trials ended, General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC), requested a new combat rifle based on reports that came from American advisers and special forces operators in Vietnam.

What they needed was a new, lightweight combat rifle, that had a lot of firepower.

Stoner saw instantly that his design, with a new cartridge, was perfect for this. It didn’t take long to downsize the AR-10 into the AR-15.

Concurrent to the redesign, Stoner worked with Winchester, Remington, and the Army to develop the .223 Remington cartridge -- the perfect lightweight, high velocity round that his new rifle needed.

There was a problem though… ArmaLite was a fairly small company. There was no way they could supply the Army with a full contract, nor did they have the kind of political connections that would help grease the way for adoption.

In 1959 ArmaLite sold the rights and designs of the AR-15 to Colt.

Later that year, Colt released the Colt 601 for civilian and military sale. The rifle would take a while to catch on in the civilian world, but it was a smash hit with American special forces units in Vietnam.

[Learn more about AR-10s in our guides about AR-10 Calibers and AR-10 vs. AR-15.]

M16 vs. M4 vs. AR-15 shooters


AR-15 Vs. M16 Vs. M4

There are minor differences in barrel lengths, materials used, etc. But these are more about choices than hard differences. Like if you make ramen with corn or without, either way -- it’s still ramen.

When it comes down to the real stuff -- the only difference between an AR-15 and an M16/M4 is that an AR-15 is semi-automatic only and an M16/M4 is select fire.

An M16 is a specific designation from the military, only rifles made by the correct manufacture to the correct standards are true M16s. They are only found in the military and are never sold to civilians.

The same goes for the M4, it’s basically an M16 just with a shorter barrel and handguard.

An AR-15 can be any length or size, but it is always semi-automatic only.

Bill Clinton signing AR-15 Ban


Violent Crime Control and Law Enforcement Act of 1994 (1994 Crime Bill)

Proposed in 1993 and signed into law by President Bill Clinton in 1994, this was a horrible law for gun owners.

Even for non-gun owners, this was a real mixed bag of bad ideas, good intentions, and failed policies.

The part that applies to firearms became known as the Federal Assault Weapons Ban. Basically, it’s what the name implies -- a ban on anything fun.

Barring the manufacture of 19 firearms by name as well as any pistol, semi-auto rifle, or shotgun that could use a detachable magazine and had two or more “evil features”.

Some of those “evil features” were basic stuff like a telescoping stock or a pistol grip. Some of them were truly silly things like grenade launchers and bayonet lugs.

I did some research writing this, and I can’t find a single time a grenade launcher was used to commit a crime.

Oddly, I did find a few times people used bayonets. That’s pretty retro.

The result of this law was that firearms development stagnated hard. Shooting sports became hard and rare. Prices went up. These were the dark times.

Thankfully, there was a sunset clause. The Assault Weapons Ban specifically said that after 10 years, the ban ended unless it was renewed.

And thankfully for all of us, it wasn’t renewed! In 2004 the ban ended.


The Industry Post-2004: A New Hope

Since the crime bill ended, the industry has exploded in growth.

The only things during those dark days of the crime bill were weird and unfun guns, basically. But once people were able to get their hands on the good stuff… we’ve been off to the races!

The National Shooting Sports Foundation estimates that 5 to 10 million AR-15 style rifles exist in the USA right now.

This just goes to show how the AR-15 has truly become America’s Rifle.

Powered by the internet, companies have popped up left and right for years. Just about anyone with a CNC mill and a dream can start turning out lowers.

It takes a lot more technical know-how, time, and investment to make great rifles though.

Over the years, the madness has died down a bit and we have established quality brands that deliver some of the most reliable, durable, and accurate firearms ever made.

[Learn more about our history and what sets Bear Creek Arsenal apart here!]


Myths and Fudd Lore

AR = Assault Rifle

The “AR” in “AR-15” stands for ArmaLite. This is a simple fact.


Only Use Is Military/Combat Applications

We’ll cover this more in a moment, but there are lots of applications for an AR-15. Shooting sports, home defense, training, hunting, and more. The fact is that the AR-15 is the most versatile firearm ever made.

Even with just a basic 5.56 NATO upper, this platform can do almost anything.

Combined with a wide range of calibers and uppers and there is almost nothing you can’t get done with this rifle.

As my favorite federal judge once said:

“Like the Swiss Army Knife, the popular AR-15 rifle is a perfect combination of home defense weapon and homeland defense equipment”.

-Hon. Judge Benitez, 2021


AR-15s Are Full Auto Weapons

There are some registered full-auto AR-15s/M16s, but they are very rare and normally sell for over $40,000 each. These are all registered under the NFA and closely tracked.

Outside of those rare guns, the only full-auto AR-15 style firearms are in the military.

The AR-15 itself is NOT full-auto, nor has it ever been.


The AR-15 Is Too Powerful for Civilian Use

This one is just bonkers because there are LOTs of guns that are wildly more powerful. .50 BMG anyone?

5.56 NATO, or any common AR-15 cartridge, are massively outclassed by all of the most common deer hunting calibers like .308 Winchester, .30-06, 6.5 Creedmoor, and by literally all of the magnums like .300 Winchester Magnum, .338 Lapua, etc. [See our guide to 5.56 vs. 308 here.]


You Can Easily Convert an AR-15 to a Machine Gun

This is majorly illegal and fairly complex. It requires several steps, a mill, a background in fabrication, and a lot of expensive equipment.

Could someone do it on their own in the home? Maybe, but it’s not painted by numbers.


The AR-15 Is Unreliable

This mythic has some truth to it, 60 years ago. The whole story is pretty long but there was a time that the M16 was not reliable and caused a lot of malfunctions and stoppages.

However, this was solved decades ago.

This was not the fault of the base AR-15 design but was caused by what the Army did to the rifle during development into the XM16 before fielding it in Vietnam.

The M16A1 was adopted in the early ‘80s and solved 99% of the issues that the M16 had.

Since then, the M16/M4/AR-15 platform has been one of the most reliable firearms ever designed.


Why Is The AR-15 So Popular?

Same reason the F150 or Camry is popular. They work, they’re a good price, they last, and they can do almost anything the average user needs it to do.

A fairly average weight for an AR-15 is about 7 pounds, often less. With that, you have a lot of firepower in your hands.

For home defense, hunting, or shooting sports -- the AR-15 is simply one of the best tools you can find.

Need more power? Get a new upper in 6.5 Grendel or 458 SOCOM.

Need to be quiet? 300 BLK is a perfect suppressor cartridge.

Need to reach out? 6mm ARC is ready to go the distance.

AR-15 Calibers Bullets


Practical Applications

Home Defense

An AR-15 puts 30 rounds (or more) in your hands, it is easy to use, accurate, and allows for very quick follow-up shots.

5.56 NATO is also great in homes due to the fact that standard 55gr ammo doesn’t penetrate drywall easily. With the high velocity and the design of the bullet, it tends to tumble and fragment quickly. This results in it being a safer cartridge than 9mm, 45ACP, or 00 Buck.

Add to it the fact that an AR gives you lots of room to add a light or mount a suppressor and you have, in my opinion, the best home defense firearm you can get.


Shooting Sports

From 3 gun to 2 gun to PRS, an AR-15 can do it all. While it is more suited for things like 3 gun, running a gas rifle in a long range competition is a ton of fun.

Sports like 3 gun and 2 gun let you train while you have fun. Learning to be faster and more accurate has real applications in self-defense, plus you can win prizes!



Be it boar or deer or something with fangs, pick the right caliber and cartridge and an AR-15 is a solid option for hunting.

Even in states that don’t allow .22 caliber or require a straight-walled cartridge, the AR-15 can still be used with just a change of the upper.

Looking at things like 6.5 Grendel or .350 Legend, there are tons of great options.

[See our complete guide to Hunting with an AR-15!]


Because It’s So Much Fun

If you’ve never taken an AR out to the range and just spent some time turning money into noise, you’ve gotta do it sometime.

I like doing it with a .22 LR upper, but 5.56 NATO is a blast as well. If you want to really live, try mag dumping some .458 SOCOM.


Best AR-15 Calibers

5.56 NATO

This is the classic, the OG, the one that almost everyone has at least one of.

For home defense, shooting sports, turning money into noise, and even some hunting applications -- 5.56 NATO is a great option that gives you lightweight bullets at very high velocities.

If you want to reach out further, heavy-for-caliber rounds are available but might not play well with the most common twist rates.

If you’re not sure what to get, get an AR in 5.56 NATO.


6.5 Grendel

One of my favorite rounds, the 6.5 Grendel is a great option for reaching out at distance and/or giving your AR more punch and power.

Flinging 123gr rounds at 2700+ FPS 6.5 Grendel will stay supersonic past 1,000 yards and deliver 1,000 ft.lbf on target to at least 400 yards.

Easy to use, looong barrel life, and fairly cheap to shoot -- the 6.5 Grendel is pretty awesome.


6mm ARC

Newer to the market than most options, 6mm ARC gives you 6mm bullets in the AR-15 platform. Perfect for sending very long distances, 6mm ARC has still yet to really prove itself.

Adopted by a nameless part of the Department of Defense, Hornady designed the 6mm ARC from the ground up as a cartridge to be sent long distances from the AR-15.

So far, it’s proven to be a really good target shooting load. If you want to get in on the new hotness, have at it!


7.62x39 Soviet

Not my favorite option in an AR 15, but still totally doable. Cheap, plentiful, and great at short ranges -- the classic AK round is now in the AR-15 also.

Although kind of limited in range, 7.62x39 has a lot of energy behind it and doesn’t cause much felt recoil making it great for things up close and personal.

Combo with a suppressor and you have a very effective home defense rifle.

It’s also very popular with boar hunting. Putting more energy into the animal than 5.56 NATO does, 7.62x39 Soviet is a great pig popper.


300 Blackout

Ballistically almost the exact same as 7.62x39 Soviet, 300 BLK is designed for the AR-15. It’s also designed for short barrels and suppressor use, so it has all sorts of tricks up its sleeve.

While ammo is more expensive than 7.62x39, it takes more common parts and requires a lot less maintenance. It’s also just flat out more reliable in the platform.

I got a lot to say about 300 Blackout so take a look!


.224 Valkyrie

Another long range cartridge, .224 Valkyrie also has the coolest name of the AR-15 cartridges.

While it’s fallen out of favor a bit lately, it’s still a very handy and capable target puncher at long ranges. I’ve shot it past 900 yards and love it.


.22 Long Rifle

I love the .22 LR cartridge and having it in an AR-15 is just awesome. Great for teaching kids, training, zapping small game, or just taking out for a fun day at the range -- a good AR-22 is simply awesome.

You can get conversion kits that use 5.56 NATO barrels making them super easy to build with your current rifle or get a dedicated .22 LR upper or rifle for better accuracy and more reliability.


450 Bushmaster / .458 SOCOM / 50 Beowulf

I’m stacking all of these together since ballistically, they are more or less the same thing.

These are big bullets for putting big holes in big targets. If you want something that will stop bears or engine blocks, pick one of these heavy hitters.

With the ballistic arc of a rainbow, these won’t get very far. But inside of that first 150-200 yards -- they hit like Tyson.

[Learn more about 450 Bushmaster and compare .458 SOCOM vs. 50 Beowulf in our new blog posts.]


Pistol Caliber Carbines

9mm, 10mm, .45 ACP, and .40 S&W are all available in the AR-15 platform and all of them are awesome.

Personally, I don’t think you can beat the simple 9mm for versatility and ease of application.

For home defense, training, or bug out bags, a 9mm AR puts a decent amount of firepower on your shoulder but won’t break your bank for ammo prices.

Need more pow? 10mm and .45 ACP are very cool PCCs.

AR-15 Mass Shootings Caution Tape


What About Crime and Mass Shootings?

There is a lie that some people will try to tell you, that rifles and especially the AR-15 are the root of all evil.

Statistics depend on who you ask, but I’ve found some fairly solid ones to share with you.

In 2019 (the most recent year the FBI has statistics for) there were almost 14,000 murders in the USA (13,927). 364 of those were with a rifle.

Not necessarily an AR-15, but with a “rifle”.

In 37 states more people were barehand beaten to death than were killed with a rifle.
Rifles are statistically very uncommon weapons of murder or crime in general.

According to Everytown, an organization that is strongly anti-gun, in 2019 there were 29 mass shootings. Only 5 were committed with an “assault weapon”, only 3 of those were AR-15s.

90% of the mass shootings in 2019 were not committed with an AR-15.

85% of the deaths caused by mass shootings in 2019 were not committed with an AR-15.

3 different stats show that rifles and by extension the AR-15 are not weapons of crime. There is no epidemic sweeping the nation of ARs going on crime sprees.

Gun Store selling AR-15


How To Buy An AR-15

The easy way is to go down to your local gun store and follow their directions. A background check, some money to the person behind the counter, and you’ll be on your way.

If you want to order online for a better deal or better selection, you’ll need to have it shipped to a local FFL.

All FFLs will transfer firearms from other stores/online stores, but they often charge a fee that can range from $5 to $150 depending on where you live (looking at you, Bay Area of California with your $100+ transfer fees!).

Before ordering your new AR, call your gun store and ask what their policies are. Some want to know ahead of time, some don’t care. They’ll walk you through the details.

Give your FFL a call, place your order, and wait for the mailman.

It’s the same as any other firearm, but it’s a pretty easy process really.

Note that local laws might make this harder… good luck.

Bear Creek Arsenal has a great FAQ page that has some more details that might help!

If you have some DIY in you, building an AR-15 is pretty easy once you get the parts for it.

Something amazing about the platform is that almost everything is interchangeable with everything.

Proprietary parts are rarely used, so mixing and matching bolt carrier groups, AR-15 uppers, AR-15 lowers, AR-15 barrels, triggers, and more is pretty simple.

Take a look at some online reviews before you buy to be sure that you’re getting a solid piece of kit at a decent price!


Parting Shots

There is a lot more to be said about every one of these topics, but this is at least a starter course for everything.

We have a ton of helpful YouTube videos and articles to help you learn even more about firearms and ARs.

If you want to dive in deeper, take a look at some of the other articles or ask questions down in the comments! For shooting tips watch the video below ⬇


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Derrell Miller
September 26, 2022
What size buffer spring does a 22 lr and a 17 hmr take ?
September 27, 2022
The .17 hmr and 22mag come with a spring and buffer which is proprietary to our uppers
May 27, 2023
BCA used to have AR-10 Side charging upper receivers with BCG in both left and right versions. NO MORE? I don;t understand. There are versions of the AR-10 complete upper that BCA does not offer. I want BCA Side Charging Uppers but am being Forced to buy entire uppers that I don't need! BCA, Bring Back the Side Charging AR-10 with BCG in Left and Right versions that can be bought without all the extra parts!! I'd buy 2 Today, if I could! I AM SURE I AM NOT THE ONLY CUSTOMER THAT WANTS THESE!!!
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