AR-15 Gas Blocks

When you pull the trigger of your AR-15, several different systems have to operate in perfect order to produce the shot. The trigger initiates a series of moving parts, leading to the combustion of the round. This round then rockets down the barrel. Some of the hot gas propelling it forward escapes through a small hole, travels backward through a tube and helps chamber the next round.

That’s a lot of synchronization. If you’ve ever tinkered with your rifle, you know that you can’t take a smoothly-operating system for granted — there is fine-tuning involved, not to mention lots of important parts.

One of the most important parts of all is the gas block. This tiny part straddles that tiny hole through which the hot gas escapes and is one of the most underappreciated, and yet impactful, components in the whole system.

A gas block’s role is to regulate the amount of hot gas coming through the hole and direct it into the gas tube, which then directs it back into the receiver. Simple, right? As it turns out, this small, sleek part handles a lot of stress. Imagine high-pressure, blazing-hot gas with lots of carbon blasting through a tiny device about the size of a class ring. Then, multiply this thousands of times to get an idea of what this part has to deal with.

In this article, we’ll discuss how a gas block works, the various types of gas blocks and what a gas block upgrade can do for your AR-15 rifle.

How Does a Gas Block Work?

The tiny porthole on the top of an AR-15’s barrel, called the gas port, is the start of a symbiotic relationship. In this case, that relationship is between the hot gas that propels the bullet and the action of the bolt carrier group. Through it, the very same hot gas that travels down the barrel will, in turn, drive the bolt backward and extract the cartridge. This gets the rifle ready for the next shot.

A gas block regulates this amount of gas. Several different types of gas blocks exist, and so there are different options for how it accomplishes this task — as well as what other functions it performs simultaneously. By limiting the amount of gas coming through the gas port, the gas block contributes to the fluid operation of the system. The gas it allows through travels through the gas tube back in the direction of the shooter, where it dives down through the gas key. This is the entrance to the bolt carrier group. Here, the downward pressure drives the bolt backward, which brings the empty shell with it. This empty shell gets ejected through the ejection port. As the bolt reaches its rearmost point and begins to cycle forward again, it grabs a new bullet off the magazine and puts it in place for the next shot.

In this complicated process, it is evident that gas pressure is the only force causing anything to happen past the initial triggering mechanism. That means gas pressure drives the bolt backward, ejecting the round and loading the next one. As you might imagine, there can easily be too little or too much pressure in this system and each scenario has its own set of consequences. We’ll discuss these shortly.

A properly-operating gas block allows the perfect amount of gas through the gas tube and into the bolt carrier group. Remember when we said gas blocks are underappreciated? That’s because they are the sole means by which you can fine-tune this system. Gas blocks directly affect the recoil, cleanliness, efficiency and accuracy of your rifle as well as how much physical energy it takes to operate it.

Benefits of Upgrading Your Gas Block

The gas block that comes stock on your AR-15 is fixed in place, meaning you can’t adjust it or tune the amount of gas making it into your receiver. Keep in mind that the amount of gas required changes with the type of ammunition you use, the weight of your bolt carrier group and buffer, and the presence of a suppressor. With the stock gas block on your AR-15, your gas system is tuned for only one setup. More likely than not, though, you’ll have tweaked some other settings or components or are using a different type of ammo.

Standard gas block systems typically allow for overgassing. This means the gas block allows more gas into the system than is necessary. The reason behind this choice is to allow the system to continue operating even when carbon buildup partially blocks the flow of gas into the receiver. With the high temperatures and carbon-rich mixture of gas, a lot of grime tends to collect as a result of overgassing. In a sense, it is an attempt to solve a problem it has created by itself — and it makes cleaning your gun a real chore.

Additionally, overgassing puts a strain on your parts. Because the bolt carrier group operates solely on gas pressure, having an excessive amount of pressure drives it back harder than is necessary. Putting extra strain on parts is expensive in the long run.

When you upgrade your gas block, you get several benefits at once. For one, you clean your gas system by putting the appropriate amount of pressure through it. This will allow less carbon to gunk up your gas block, gas tube and receiver. You also put less strain on parts, increase the longevity of your bolt carrier system and more.

There are other benefits, as well, including customization options. Many gas blocks are typically made of lightweight metal — for weight savings, since every ounce makes a difference — and they come in different sizes, colors, finishes and designs. You can customize to your heart's desire and make sure your gas block fits underneath your handguard and rail.

Types of Gas Blocks

The type of gas block you choose will depend on several factors. How often do you change ammo? Do you often change other components, including suppressors? Do you use the gun for competitive range shooting or are you involved in active combat or law enforcement? In this section, we’ll outline the common types of gas blocks available.

Standard Gas Blocks

Standard gas blocks are so named because they have exactly one setting and cannot be adjusted. Even so, upgrading from your rifle’s stock gas block to another standard gas block is still beneficial. This is because a smoothly-operating standard gas block is an excellent tool for those who have found a setting and would like to stick to it.

An advantage of standard gas blocks is that they are simple and easy to operate. If you tend to use a particular type of ammo and are happy with your bolt carrier group and the weight of your buffer and buffer spring, then you may want to consider a standard gas block.

These gas blocks slip on over the end of the barrel and fit over the gas port. Two to four screws typically hold them in place, which generally work best with a thread lock. This ensures the gas block won’t move under the force of recoil and the tremendous pressure it must contain. Alternatively, you may have a dimpled barrel that holds the gas block securely.

Standard gas blocks are generally cheaper than adjustable gas blocks because they have fewer parts. You may also prefer them for their aesthetic sleekness. Whatever your reason, standard gas blocks are a great choice for those with a more consistent setup.

Adjustable Gas Blocks

Installing an AR-15 adjustable gas block is an upgrade you are unlikely to regret. If you have altered the componentry in your gun at all or use different types of ammo in different situations, an adjustable gas block is a key to making your gun shoot smoothly.

The idea behind an adjustable gas block is that an aperture, typically operated by a screw, adjusts how much gas enters the gas block. By installing one, you bring the benefits of a new gas block to a whole new level in that you can now make quick adjustments and tune your rifle on-the-fly.

By dialing-in the perfect settings on your rifle, you will experience several improvements:

• Less recoil: One huge advantage of adjustable gas blocks is that they allow you to optimize and minimize your recoil. That means your gun will deviate less after each shot, requiring less effort to set up for the follow-up shot. This reduces fatigue and improves accuracy.
• Less wear on your gun: Instead of overgassing and running your rifle harder than necessary, you can give it exactly as much force as it needs. Your bolt carrier group will thank you, as will your wallet when you don’t have to replace parts as frequently.
• A cleaner gas system: Just as with the standard gas block, an adjustable gas block should be set up to minimize carbon build-up while still providing sufficient power to the receiver. This means less soot and easier cleaning.

Low-Profile Gas Blocks

The gas block is seated on the barrel of the gun — but then again so are a lot of other parts. There are scope systems, perforated handguards, rails and more — and you don’t want your gas block getting in the way of any of it. AR-15 low-profile gas blocks are a great way to take advantage of an upgraded shooting experience without cluttering up the front end of your gun.

Both standard and adjustable gas blocks come in low-profile form. Engineered and machined to exact precision, these parts do their job while taking up the least amount of space necessary. They are also elegant and simplistic in their design and come in several different styles.

Check out the wide selection of low-profile gas blocks available to find one that will work with your setup. Be careful to measure the space allowance on your barrel before purchasing.

Sizing Guide to Gas Blocks

Gas blocks are designed to fit on different-sized barrels. Certain designs will only be available in one or two sizes, though, so it is important to know the size of your barrel before upgrading. Gas blocks tend to come in several different sizes: 0.625”, 0.750”, 0.875” and 0.936”, for example. The most common fits are as follows:

• Gas blocks for pencil barrels: Pencil barrels are skinny, slender and lightweight — and that makes them an excellent choice for game hunting and other situations where you have to carry your gun for extended periods. They usually take a 0.625” gas block. Because they are skinny and lightweight, pencil barrels also tend to heat up and cool down more quickly than thicker barrels, which can lead to warping. This makes them less ideal for applications where repetitive, accurate firing is needed. Choose a gas block for a pencil barrel with this in mind.
• Gas blocks for standard barrels: A standard barrel for an AR-15 rifle rides the line between pencil barrels and bull barrels. These barrels are a happy medium between accuracy and agility, as they absorb and dissipate heat relatively well and are not as heavy as bull barrels. They accept 0.750” gas blocks, which are also the most common size available.
• Gas blocks for bull barrels: Bull barrels are a larger, heavier option for your AR-15. These barrels house larger gas blocks, such as 0.875” and 0.936”. Note that these sizes are not as widely available as standard 0.750” gas blocks. They are great for firing ranges and applications where you can set your gun down to aim. The bull barrel is larger in diameter and the walls of the barrel are thicker. This lets the barrel absorb a lot more heat without warping and lets you fire for longer. However, there is also much more metal from which heat must dissipate, meaning these barrels take longer to cool down. Choose a gas block that matches the barrel’s size and is optimized for its abilities.

AR-15 Gas Blocks for Sale at Wing Tactical

At Wing Tactical, we have a large and ever-increasing selection of rifles, components and supplies for you to choose from. Whether you are a law enforcement officer, in the military, a dedicated hobbyist or an active competition shooter, our store is the best way to give yourself an edge.

When you upgrade your gas block, you also upgrade your accuracy, agility, fatigue level and the ongoing cleanliness of your gun. We offer low-profile gas blocks in both standard and adjustable styles, as well as in different materials and finishes to suit the visual style of your AR-15.

We are your ultimate source for weapons and tactical gear. Shop online and peruse our incredible selection of standard and adjustable gas blocks, as well as rifle upgrade kits and similar products. We sell all-new inventory and everything we sell is backed by a 30-day satisfaction guarantee or your money back.

Come to Wing Tactical and put yourself ahead of the curve — we’ve got the gear you need.