The Best AR 15 Mods: 18 AR Upgrades for Your Rifle

From AR 15 mods to AR 15 attachments and AR 15 upgrades, this guide will provide a logical way to upgrade and improve your rifle, so you can create the best AR build for you.

The AR platform is the most popular style of rifle in the U.S. because of its user-friendly controls and modular design. It's easy to customize without a high degree of skill or gunsmithing experience. Additionally, ith as a massive amount of aftermarket parts you can use to fully transform a stock rifle into a completely custom model that suits your specific needs.

You can add accessories like an optic or flashlight to any AR, or you could replace a major component central to the rifle's operating system like the bolt carrier group (BCG). Still, that doesn't make the task any less daunting or expensive.

AR 15: A Short History

The AR design has evolved since its introduction in the 1950s. Originally, the rifle, called the ArmaLite 15, was designed for and adopted by the U.S. military. It was called the M16. The main difference between the two is the M16 has a select-fire option whereas the civilian AR platform is a semi-automatic rifle, meaning it can only fire one round at a time.

However, since design patents for the AR15 have expired and entered the public domain, they're available for use by any gun or gun parts manufacturer. Today, nearly 20 million AR rifle designs are circulating in the commercial market. Those millions are made by numerous manufacturers and consist of even more variants. Because of that fact, an AR 15 isn't always called an AR 15.

There are lots of different names floating around. A lot of times there's an AR- or a -15 tacked on somewhere. However, there are general terms like AR pattern, AR platform, AR15, Modern Sporting Rifle (MSR), or just simply AR. No matter what they're called, they all have the same core elements.

The Core Elements of an AR

A common AR platform can be best summarized as a gas-impingement, magazine-fed rifle chambered in 5.56mm or .223 Remington, but they're available in a variety of other chamberings as well. Traditionally, it has all the same features as a standard-issued M16 (except the select-fire option, of course), such as fixed sights and a butt stock.

Today, almost all AR manufacturers offer their own take on the design and include features like an adjustable butt stock, railed handguards, and removable iron sights.  They usually also offer a no-frills variant, so buyers have an easier time building out the rifle. With it, you can add features you want instead of paying for features you don't want.

AR 15 Attachments, AR 15 Mods, and AR 15 Upgrades

An AR 15 breaks down into two major groups: the upper receiver and the lower receiver. Both receivers have key components that make the gun operate as well as features and controls that allow you to effectively use it. How an AR owner customizes their rifle depends on their preferences, ability, and experience.

If shooters want an easier time shooting, they'll add or remove accessories. If they want to improve ergonomics, they'll modify the rifle's controls. And, if they want to improve the rifle's performance, they'll swap out operational components.

Handguards

Handguards on the traditional design served one purpose: protecting your hands from the barrel when it got hot. But somewhere down the line someone figured out how to make this feature more useful.

Today, upgrading the handguards means adding a rail or locking system. The benefit is it allows you to add attachments, reduce weight, improve ergonomics, etc. New AR 15 handguards can range in price from under $70 to more than $300. Common attachment systems include:

• Picatinny: The Picatinny rail system is the most popular. It was originally designed for the military and intended for optics, but it can be found on all four sides of the handguard for mounting other accessories.
• M-LOK: The M-LOK, or Modular Lock, is a patented locking system by Magpul Industries. It is a series of slots that allow you to either mount a piece of rail (for an accessory) or an accessory directly.
• KeyMod: The KeyMod locking system is an identical concept to the M-LOK, but instead of slots, it has keyholes.

Interestingly, the U.S. military compared M-LOK and KeyMod. While both showed battlefield capability, M-LOK was deemed better for their needs, according to Soldier Systems. However, you probably won't be conducting stress tests on your rifle or gear.

Generally, you have two options to replace the traditional handguards. First, you could replace it with another two-piece system by simply sliding them in place. Second, you could add a free float system, which attaches directly to the receiver. However, the latter requires removing or replacing other parts as well.

Sights

Traditional AR iron sights include a rear sight and a front sight. The rear sight has two ghost rings, a small pinhole for day and a large one for night. You can adjust it for windage and elevation. The rear sight was fixed to a carrying handle, so if you wanted to remove the sight, you had to modify the upper receiver. The handle is less common nowadays.

The front sight is a little post that's also adjustable for elevation. On a traditional AR, it's held in place by a few pins near the front of the barrel. The component that holds the post also holds the gas block, the entry point for gas to enter the gas tube which channels it to the bolt. If you replace it, you'll also have to replace the gas block.

At this point, we'll presume you have a rail system. If the rail system runs along most of the barrel, you have the option to mount iron sights, an optic, or both. For instance, you can get flip-up sights, which flip up or down depending on when you want or need to use an optic. They function the same as traditional AR sights.

You can buy the front and rear sights separately or as a pair. Either way, you will probably spend between $100 and $200 on new iron sights. Then, optics run the gamut. You can get a rifle scope that magnifies your target or a quick acquisition optic like a red dot.

Buttstock

Traditional AR 15s had a faux wood, fixed buttstock, but nowadays, an adjustable polymer buttstock is just as common. Are there AR 15 upgrades from there? Absolutely.

There are stocks available with a lot more features than just adjustability. Some stocks offer compartments, cheek rests, and alternative sling configurations.

A new AR15 stock is another relatively inexpensive upgrade for the benefits you get in return. Most adjustable stocks cost less than $60, but you could also spend a lot more than $250 depending on features and construction materials.

Pistol Grip

Of all the features on an AR, the pistol grip is one of the most intuitive. It's simple yet extremely functional. How can you improve it?

You can find AR15 pistol grips that are thicker, thinner, have finger grooves, and ones with a tiny compartment for batteries or whatever. Or maybe you want it to match the color of other components on the rifle.

The molded part often constructed from rubber, polymer, or G10 tends to cost around $25.

Grips

A foregrip is one of the easiest AR 15 mods to make. There are a variety of AR15 front grips available. The designs range from an angled foregrip that you cup to a vertical foregrip that you grab, much like a pistol grip. All things considered, it's an inexpensive upgrade for the benefit of better control over your rifle. It often costs less than $50.

Trigger

If you shoot long enough, you're likely to develop an opinion about trigger pull and want to make this AR 15 mod. Triggers generally vary by brand, quality, shape, and pull weight as well as how easy it is to replace.

Replacing an AR 15 trigger ranges from easy to complex depending on how much you want to take it apart. Lots of companies offer drop-in triggers, meaning it literally just drops in place and then you refasten it to the receiver with some pins.

Generally speaking, you'll need to spend between $150 to $300 for a drop-in trigger.

Charging Handle

The charging handle allows you to manually retract the bolt and do things like charge the rifle or clear the chamber. It's common to upgrade an AR with a charging handle that's easier to grip.

An oversized or extended handle allows you to engage it quicker and with gloves on. This AR 15 upgrade is really simple. You just take the old one out and put the new one in. Most cost less than $50.

Bolt Release

The bolt catch, the internal part of the bolt release, locks the bolt to the rear. It happens when you manually hold down the nipple below the button. It also happens automatically when the bolt encounters an empty magazine. However, the bolt release releases the catch and sends the bolt home when you hit the bolt release button.

Much like the charging handle, you might want to replace the bolt release with one that has a larger button. You can replace it by removing and reinstalling a pin. Since it's a fairly small part, you should be able to find one you like for around $25.

Safety Selector

The safety selector engages and disengages the safety. Common reasons for a shooter to make this modification is to give their AR ambidextrous, or left-handed, controls or to change the degree of throw. Some rifle manufacturers make their selector switches reversible or ambidextrous, but if they don't, there are plenty available by gun parts makers. Most new selector switches will cost anywhere from tens of dollars to around $150.

Magazine Release

When you insert a magazine into the mag well, it will automatically lock into place on the magazine catch, and then the catch releases when you press the magazine release button. It's the same concept as the bolt release.

You generally don't need tools to remove it. The magazine catch screws into the magazine release button. For the cost, it depends on if you buy your new AR mag release in pieces or as a whole kit. Each part might only cost a few bucks whereas a kit might cost between $25 and $75.

Bolt Carrier Group (BCG)

The bolt and bolt carrier are two different pieces, but they can't function without one another. The bolt contains the firing pin and fits inside the bolt carrier while the bolt carrier fits inside the upper receiver and interacts with the gas tube.

It's common for shooters to replace small parts like a cam pin or firing pin and it's also common to replace the entire BCG with another one constructed from more durable or moisture-resistant material.

Replacing it is as easy as replacing the charging handle. Take the old one out and put the new one in. It's most common to see it listed in the $70 to $150 range.

Barrel

Changing an AR15 barrel looks like an easy AR15 mod because it screws on and off, but you need to be careful. The threading that connects the barrel to the receiver is very tight, so if you do it incorrectly, you risk misaligning the threads.

The incentive to changing the barrel, though, is you can get a nicer one that's more suitable for your shooting needs. One with a higher twist rate, heavier construction, different length, or made from better materials. The price generally ranges from $150 to $300.

Muzzle Device

Since you just dished out the cash for a new barrel, you might want to add a muzzle device, which twists on and off with a wrench. Common types include a flash hider to reduce muzzle blast; a muzzle brake to reduce the already low felt recoil; or a compensator to limit barrel rise.

Although they're tiny and their effect may be subtle, a new muzzle device costs more than you would think. Most of them are cut with unique or proprietary patterns to control expelling gas. That highly specialized feature tends to drive up the price. You'll find most costing between $60 to $100.

Gas System

If you've upgraded or changed everything else up to this point, you basically have a new rifle, so what are a few more changes? The gas system consists of a gas block and a gas tube. There are multiple reasons for wanting to change the gas block.

Sometimes it's because you want a slimmer rail system. Other times, you want to shoot specific ammunition or use a suppressor. In those cases, you'd probably install an adjustable gas block, which allows you to control how much or how little gas flows through the gas tube. Replacing it requires removing pins and maybe other parts of the rifle.

The gas block, especially an adjustable gas block, is something you should seek further guidance on before installing. For all that it does, the cost is surprisingly low. A low-profile gas block can cost you as little as $20 and you can find an adjustable one for less than $100.

Buffer Assembly

When the bolt carrier moves backward, it presses against the buffer and buffer spring that sits inside the buffer tube. You would replace the buffer or spring when they wear out, or if you change to a lightweight BCG, barrel length, or caliber. A buffer tube kit will run you around $40.

Ejection Port Cover

The traditional AR has an ejection port cover. It's a little metal flap that covers the chamber and in turn protects the bolt from dust or dirt. That's really all it does, but some people buy a cover with an aesthetically pleasing design. A replacement will run you around $10, but something with print or etching might cost more.

Forward Assist Button

The forward assist exists to nudge the bolt forward if it doesn't slide into place. You can replace it, but if you constantly need to use it, you might have a problem with some of the operational components. There's actually an ongoing debate on whether or not the forward assist is useful anymore. If you do decide to change it, it might cost you around $25.

AR 15 Attachments

It's worth mentioning that there are accessories that make the rifle more enjoyable to shoot. Magazines, for example, can affect the shooting experience. For instance, some high-quality magazines deliver a consistent performance throughout any type of treatment. Others offer a higher capacity limit.

Another honorable mention is a sling. The traditional canvas sling is fine, but there are other much more functional slings that have quick detachment or adjustment features, padded sections, and even carrying options.

Yet another is a weapon light, especially if you have a duty rifle. Holding a flashlight and pistol isn't too difficult, but holding a rifle and a flashlight? Pretty tough.

Customizing... No, Personalizing Your AR

By the time you're done with all your AR 15 mods and AR 15 upgrades, you will have spent a lot of money. Hopefully, this guide gave you a better idea of how to prioritize your purchases, so you know where to start and what to do for when you want to build your dream 3-gun or plinker, or just modify your upper or lower.

*Always check your local laws before modifying your rifle to ensure legal compliance.