The 7 Best AR-15 Gas Blocks In 2024

Installing and upgrading an AR gas block will reduce your rifle’s recoil, increase accuracy and reliability, and open up a wide range of customization options. In this article, I’ll explain why an aftermarket gas block is one of the best upgrades you can make on your AR-15. I’ll also talk you through what to look for to ensure your new gas block is of the highest quality.

What is a Gas Block and How Does it Work

The gas block on an AR1 5 is responsible for how much gas is directed back to work the action each time the weapon is fired. It’s placed over a hole on the top of the barrel of an AR-15 rifle or carbine.

The performance of the gas block directly impacts the rifle’s recoil, accuracy, and reliability.

How does it work exactly?

Well, simply put, the gas block is designed to direct the gas from firing the bullet from the barrel through a port, into the block, and down the gas tube.  When the weapon is fired and the powder in the cartridge explodes, the bullet is driven through the barrel and past the hole. The gas block can be described as a valve that controls how much hot gas will be directed back to the receiver. This will work regardless of which ammo you use, and even if you use a heavier or more powerful load.

Some of the hot gas will pass through the hole, enter the gas block, and will then be moved down the gas tube. The gas tube will then direct the hot gas back towards you and the receiver.

The force of the gas then moves the bolt carrier group to auto-cycle the next round into the chamber. The bolt is pushed backward which causes the cartridge to extract ahead of a new round being loaded from the magazine into the chamber. This allows the weapon to be fired again.One great quality that AR-15 rifles have is their ability to be tuned for better performance and to be customized to no end. This is thanks to the large range of aftermarket parts available such as gas blocks.

Our Guide to the Top Best 7 AR-15 Gas Blocks on the Market

Here are the best AR 15 gas blocks that are on the market this year. We have tested and reviewed each one to figure out which product is the best choice for your AR-15. The listed pros and cons will help you to compare all the options.

Reasons to upgrade your AR-15 gas block

An aftermarket gas block from a reputable industry professional will offer a variety of advantages over a standard block. A low-quality gas block will bleed too much gas in the barrel which won’t leave enough pressure to cycle the action.

To put it another way, a bad gas block will result in too little energy left to reliably eject and chamber a new round. A new, high-quality AR 15 gas block will solve this problem and bring other benefits too.

Since the gas block regulates the amount of gases released during firing to cycle the next round, upgrading this can make your AR’s cycle much smoother.

Other benefits you will experience from upgrading your AR-15 gas block are:

1. Reduced recoil
2. Reduced wear
3. More ease of use
4. Better cleanliness
5. Increased accuracy
6. An overall more reliable rifle

How to choose an AR-15 gas block

Types of gas blocks

There are two main types of gas blocks: standard and adjustable. Whether you choose a standard or adjustable gas block will depend on what you use your rifle for, and how frequent that use is.

Standard gas blocks

Standard gas blocks are good for duty rifles as they give very reliable operation. It’s worth noting that you can find very high-quality standard gas blocks too. If you are a casual shooter then these may be the best AR 15 gas blocks for you.

• Standard gas blocks are the simpler option, which is why many shooters opt for them.
• However, a standard gas block only allows a fixed amount of gas to travel through the tube. The problem with this is that it usually allows through more gas than is needed.
• If the hot gas that’s passing through carries with it a lot of carbon, it can cause the interior of the rifle to clog up.
• By sending too much gas down the receiver, the system will still run reliably but will get rather dirty. This will result in more wear and tear being inflicted on your AR 15. It will also wear out quicker.

Adjustable gas blocks can solve this problem.

For serious shooters, especially those who use their rifles for competition or target shooting where precision is highly valued, an adjustable gas block will give you that perfect accuracy you need.

• An adjustable gas block allows you to more carefully fine-tune the amount of gas that enters the receiver.
• By doing this, the bolt will receive the right amount of gas that it needs.
• You can then decrease how much carbon gets into the system as well, so cleaning your AR-15 will be much less of a hassle.
• They also create far less recoil than a standard model. Moreover, they enable a direct gas impingement to run much more smoothly.
• The biggest drawback to these adjustable versions is that they require more maintenance and take longer to operate.

Types of adjustable AR-15 gas blocks

There are two main types of adjustable AR 15 gas blocks that you will come across. Your new adjustable gas block will either be a low profile style or a front sight style. Let’s explore the differences between the two.

Low profile gas blocks

Low profile adjustable gas blocks give you many different adjustment points, allowing for almost maximum adjustability. These gas blocks are compact and designed to fit under long free float handguards.

• Alow full-length free-float handguards to be used on your rifle when you install them.
• Can replace A2-style front sights if you’re looking to move away from traditional drop-in handguards.
• As these types of gas blocks are made with less material, meaning they have less mass, any imperfection or weakness in the medium can result in the gas block failing prematurely.

If opting for a low profile system, look for gas blocks that are precisely machined from high-quality stainless or carbon steel and feature tough finishes like phosphate and nitride.

Front sight bases

Railed gas blocks, also known as Picatinny front sight gas blocks, are pretty much low profile gas blocks with a Picatinny rail installed on them.

• This front sight style is useful if your rifle doesn’t have a front sight or the option to install one. With this front sight base, you can easily install it by adding the gas block.
• Or, you can go the traditional route and get the old-style front sight base that has that iconic a-frame sight right on the gas block.

This system is a brilliant choice if you have a set of detachable flip-up iron sights you’d like to use. It’s worth keeping in mind that this Picatinny rail will often be at a much lower plane than the upper receiver.

Gas block mounting systems

As well as the different types of gas blocks, you will also find different mounting/attachment systems for AR 15 gas blocks. There are two common methods for attaching a gas block to the barrel – either Slip-on or, Clamp-on style gas blocks.

Slip-on style gas blocks

Most popular type and usually more stable and reliable.

• Slip-on models slide down the barrel and are anchored by set screws on the underside.
• The downside to slip-on gas blocks is that the tolerances can be very tight. You’ll likely need to hone the gas block a little bit so that it can slide into place.

Clamp-on style gas blocks

• Also, slide down the barrel to position it into place. However, with this type, there is a small gap in the gas block which makes it easy to accommodate for tolerances, unlike the slip-on models.
• The negative aspect of clamp-on gas blocks is that the clamping action isn’t as strong as the slip-on style, and they tend to be a bit bulkier too.

When and how to tune an adjustable AR-15 gas block

Over-gassed rifles mean more gas flows through the system than necessary. Over-gassed rifles will produce more recoil. More gas flowing rearwards means more force, and more force results in feeling more recoil.

Recoil makes it harder to control your rifle, which significantly reduces your accuracy. Recoil will also wear out your internal components faster. An over-gassed gun is also going to get hot and dirty much quicker. That extra carbon build-up also makes the rifle less reliable and increases the chance of rifle failure.

How to adjust a gas block

An adjustable gas block allows you to fine-tune the gas needed, and the procedure is pretty simple. If you notice your rifle is over gassed, it may be worth investing in an adjustable gas block and fine-tuning the gas flow.

Here’s how to do so:

• Load a magazine with one round to test how it cycles. Look for how reliably the round cycles the action and if the bolt locks to the rear with an empty magazine.
• If the weapon cycles perfectly and the bolt locks to the rear, restrict the gas flow by a ½ turn of the adjustment screw.
• Repeat loading and firing, observing cycling and the bolt locking to the rear. Restrict the gas system another ½ turn.
• Continue repeating until the bolt does not lock backward on an empty magazine. Once you reach this point, open the gas system ¼ turn.
• Repeat the test. If it locks back then this is your optimal gas setting. On the other hand, if the bolt still fails to lock to the rear, open adjust the system another ¼ turn, and this will be your optimal setting.
• Lastly, run a magazine through the weapon to ensure it cycles reliably.

AR-15 gas block sizes

Gas blocks come in various sizes. For the best fit, ensure your gas block is the appropriate size for your barrel.

• .750 – Best size if your rifle has a medium or standard barrel.
• .936 – Most suited to heavy bull barrels.
• .625 – Ideal for pencil barrelled rifles.
• .875 – Used for customized barrels.

Gas block material options

Gas blocks are constructed with different materials. These are the 4 most common ones:

• Aluminum – This is the weakest material so not recommended for a gas block. Repeated heat cycling would likely cause an aluminum gas block to quickly loosen.
• Carbon Steel – This is probably the most popular choice for an AR 15 gas block. It’s durable and stays secure after repeated heat cycling. However, carbon steel is prone to rust so it may erode quicker than other materials.
• Stainless Steel – This is much more resistant to rust than carbon steel, and it’s very chemical resistant too. It also gives superior durability over carbon steel. However, it’s more difficult to machine and is more expensive.
• Titanium – This is the most durable material and it is extremely chemical and corrosion-resistant. It’s much stronger than carbon steel but also 40% lighter. However, as it’s the best quality, it is the most expensive.

AR-15 gas block finishes

The purpose of the finish on a gas block is to protect it from wear and corrosion. As gas blocks are subjected to very hot, high-pressure gases, the finish is an important consideration.

There are numerous finishes that a gas block may have. In most cases, phosphate or nitride finishes are more than adequate, as they give good enough protection from corrosion and heat. A phosphate finish is the most popular choice because of its cheap price, however, nitride is stronger.

Furthermore, some materials like titanium and stainless steel don’t require a finish as these materials are already corrosion resistant.

Other ways to upgrade your AR-15 gas system

As well as installing a new gas block, there are two other upgrades you can make to your gas system.

Gas tubes

This is an essential upgrade if you’re using a direct impingement system. When hot gases pass through the gas block, they then travel through the gas tube to the receiver. These hot gases are subjected to extreme pressure, high temperature, and dirty carbon. Upgrading to a high-quality gas tube will resist the corrosion and gunk created from this, and make your rifle easier to clean.

Piston Kit

A piston kit is an alternative to the direct impingement system that works with less heat and less corrosive gas entering your receiver. It’s a worthy upgrade if you want a cleaner operation.

Buffer system

Turn the buffer system with the right weight to match your gas system.

These options will make your gun run more smoothly, increase its reliability, and reduce wear and tear.

How to install a pinned AR-15 gas block

If you’re unsure how to install your new pinned/ set-screw AR 15 gas block? In this section, I will be covering the gas block and gas tube installation with the ones that I purchased for my AR-15.

There are a tremendous amount of different low-profile gas blocks available on the market today, but these two appear to be the most popular: clamp on style and set screw style. I built my AR-15 upper receiver with a clamp-on-style gas block – Be sure to also check the instructions that came with the product. Let’s get started.

1. Before you install the gas block, the first thing you will want to do is install the gas tube into the block itself. This is done by inserting the gas tube into the gas block and driving a small roll pin into place, which ensures that the gas tube isn’t easily removed. To make these steps a little easier, you may want to check out the Geissele Gas Block Roll Pin Tool and Gas Block Pin Punch Set.

   

2. After the gas tube is installed properly, slide the gas block over the barrel. Be sure to check the gas tube alignment into the upper receiver and for proper alignment with the gas port in the barrel. I typically slide my bolt carrier into the upper receiver to make sure that the gas tube does not bind or snag on the gas key. It should fit without friction.

   

3. To help with aligning the gas block to the gas port on the barrel, I marked a pencil line down the center of my gas block, and down the center of the barrel. Then I lined up both marks and tightened down the screws on the gas block with some thread lock.

   

Which is the best AR-15 gas block?

From reviewing the 7 AR-15 gas blocks above, I realized how much gas blocks can vary greatly in quality and fit. The one that easily stood out from the rest was the SLR Rifleworks Sentry adjustable gas block.

This block is super easy to install and gave no issues with fitting, unlike many of its competitors. It works flawlessly, is extremely reliable, offers 15-position adjustability, plus 4 different size options. Although this is one of the most expensive options, I think in this case, it’s worth spending a bit more to get the very best on the market.

By following this guide, you too will have learned how to find the best AR 15 gas blocks on the market. From the information in this article, you’ll have deepened your understanding of the different factors of gas blocks, enabling you to choose the best AR 15 gas block.