The Best 300 Blackout Gas Systems for Building a Reliable 300BLK Rifle

Last Updated on January 12, 2021.

300 Blackout gas systems can be a bit finicky. It’s nothing crazy complicated. But the gas system in a 300BLK rifle isn’t quite as plug-and-play as a 5.56mm gas system. Researching the best 300 Blackout gas systems before you start building is a smart move.

However, gas systems usually don’t come complete. You have to get a gas tube and a gas block.

The gas block is the most critical part, since that’s what determines how much gas bursts into the gas key on your bolt carrier.

So, to help you build the most reliable gas system possible, we’ve gathered the best 300 Blackout gas blocks and the best 300 Blackout gas tubes. All you have to do is choose a gas block and a gas tube. Then put them together to create the best 300 Blackout gas system for your rifle.

Our Best Choice

SPOILER—if you want us to make the decision easy for you, get these two components:

  1. SLR GB7 .750 Non-Adjustable Micro Gas Block.
  2. ODIN Works Gas Tubes.

These two components will give you a reliable 300 Blackout gas system that will work for most 300 Blackout rifles. Just make sure you get the correct length of gas tube.

If you’d like to see what we’ve got and choose for yourself, keep reading. We’ll cover all the components for building the best 300 Blackout gas systems.

Top 300 Blackout Gas Systems on the Market Today

The Best 300 Blackout Gas Systems Reviews: Not Too Much, Not Too Little. Just Enough Gas.

The overall best components for building the best 300 Blackout gas systems will be covered first in each section. The other best components will be presented in order of price, from most expensive to most affordable.

Gas blocks will be covered first. Then we’ll move on to the gas tubes.

Let’s gas this thing up.

1. SLR GB7 .750 Non-Adjustable Micro Gas Block - Overall Best 300 Blackout Gas Block

The SLR GB7 .750 Non-Adjustable Micro Gas Block is the simplest gas block solution for your 300BLK build. All you have to do is install this gas block, and (most of the time) your rifle will run reliably.

The main thing is that this is a super low profile gas block. It won’t interfere with your handguard, regardless of which handguard you use.

Additionally, this gas block is finished with melonite QPQ. It’s a more durable and corrosion resistant coating than the mil-spec phosphate finish. That way your gas block will hold up for as long as possible, probably longer than the other components in your rifle.

And this gas block is machined from 4140 billet steel, which is strong and corrosion resistant on it’s own. That further enhances the lifespan.

Lastly, this gas block uses SLR Rifleworks’ Nitro Express gas port, which delivers enough gas to run your bolt unsuppressed. But it doesn’t get too overgassed when you’re running suppressed.

Obviously, an adjustable gas block is ideal for shooting both suppressed and unsuppressed. But this gas block offers a good compromise for those who don’t want or need an adjustable gas block.

Overall, this is a super long lasting and well tuned gas block that will work for 300 Blackout rifles that have a standard gas system length (pistol or carbine length).


  • Machined from 4140 billet steel for excellent lifespan and corrosion resistance.
  • Melonite QPQ finished for additional corrosion resistance and lifespan.
  • Tuned gas port supplies enough gas for unsuppressed shooting without being too overgassed with a suppressor.
  • Affordable.


  • Non-adjustable gas block isn’t ideal if you often transition between suppressed and unsuppressed shooting.
  • Mounts with a single set screw.

2. Seekins Precision Low Profile Adjustable Gas Block - Budget Adjustable 300 Blackout Gas Block

If you want an adjustable gas block for your 300 Blackout gas system, the Seekins Precision Low Profile Adjustable Gas Block is the best blend of quality and affordability.

This gas block is machined from 1144 steel, which is stronger and more corrosion resistant than most competing gas blocks.

And the steel is protected with a salt bath nitride finish to improve corrosion resistance and lifespan.

And this is a low profile gas block. This gas block will fit under almost any handguard.

That stuff is mostly table stakes, though. The adjustability is the big deal.

This gas block adjusts with a single allen screw on the side. There are no steps or settings. You just adjust the screw in or out to set the gas flow.

The adjustment system is good because it’s super preciseYou can set the gas flow exactly where you need it.

On the other hand, if you want to have two settings, you’ll have to measure your settings in the number of turns. It’s not quite as quick as a gas block with preset stages.

But, this Seekins Precision model is a really affordable adjustable gas block. And it enables you to be very exact with how much gas you give your rifle, which is handy if you use a non-standard gas system length or a barrel with a tuned gas port.

If you want the most precise and affordable gas system, this gas block does the trick.


  • Machined from 1144 steel for more strength and corrosion resistance than most other gas blocks.
  • Salt bath nitride finish gives you the longest possible lifespan.
  • Precise gas adjustments via an allen screw on the side of the gas block.
  • Fits under almost any handguard.


  • Gas system is precisely adjustable, but not as convenient as a gas block with preset stages.
  • Adjustment screw can be tricky to reach if your handguard doesn’t have good access holes.

3. SLR Sentry 7 .750 Adjustable Gas Block - Adjustable 300 Blackout Gas Block

If you want the best adjustable 300 Blackout gas system, period, the SLR Sentry 7 .750 Adjustable Gas Block is the way to go.

In terms of build quality, it’s just as good as any standard gas block.

It’s machined from 4140 steel. It’s finished in black melonite to enhance the corrosion resistance and lifespan. And it has 2 set screws for secure mounting.

All the standard durability features are there.

But the adjustment system is one of the best you can get.

The gas adjustment system is a 15 stage adjustment system. Even though there are preset gas flow settings, there are a lot of them. So you can still set your gas flow very precisely.

Additionally, the gas system is adjustable from the front. As long as your handguard is open on the front end, you’ll be able to easily reach your gas adjustment screw. There are very few handguards that present access issues for adjusting this gas block.

If you’re building a 300 Blackout suppressor host, but want to quickly swap between suppressed and unsuppressed operation, this is the best gas block you can get. No other gas block offers such precise adjustment with preset stages for quick adjustment.


  • Machined from 4140 steel for industry standard durability.
  • Black melonite finish offers excellent corrosion resistance and lifespan.
  • Adjustable gas system has 15 adjustment settings for precise gas flow adjustment.
  • Adjustment screw can be easily reached from the front of the gas block.


  • Expensive.

4. ODIN Works Gas Tubes - Overall Best 300 Blackout Gas Tube

Usually, your gas tube isn’t the source of your gas system issues. It’s usually the gas block or bolt carrier. But that doesn’t mean you should skimp on your gas tube.

ODIN Works Gas Tubes are easily the most cost efficient option when it comes to gas tubes. They’re well built and reasonably priced.

These gas tubes are manufactured to mil-spec dimensions. And they’re made of higher quality stainless steel than is specified in the military specifications.

So this gas tube is just as reliable and longer lasting than a standard mil-spec gas tube.

Lastly, these gas tubes come in every length, which is pretty important since many 300BLK gas systems use a pistol length gas system. So you can get this gas tube to fit whatever gas system length you have.

Also, this ODIN gas tube comes with a roll pin, just in case your gas block doesn’t come with one.

Overall, there’s nothing flashy about this gas tube. It’s just a quality gas tube that’s not too expensive.


  • Manufactured with excellent quality control to ensure that your gas tube is true to mil-spec dimensions.
  • Made from higher quality stainless steel than is required by military specifications.
  • Available in the most common 300 Blackout gas system lengths.
  • Includes a roll pin, just in case your gas block didn’t come with one.


  • No additional corrosion resistant finish.

5. PSA Custom Nitride Pistol Length Gas Tube - Value 300 Blackout Gas Tube

If you want an upgraded gas tube for your rifle, the PSA Custom Nitride Pistol Length Gas Tube is pretty much the best gas tube you can get for the money.

It comes in a carbine length model too: PSA Custom Nitride Carbine Length Gas Tube.

For the most part, this is a standard mil-spec gas tube.

The dimensions are mil-spec. And the stainless steel is mil-spec.

The upgrade is in the nitride finish. The nitride finish makes the stainless steel more corrosion resistantThat way your gas tube will last longer than a classic stainless steel gas tube.

Also, I think a black gas tube looks cooler than a silver gas tube. Though, that’s obviously a subjective statement.

But, even if you don’t care what color your gas tube is, this Palmetto model offers the most durability and longevity for the money.


  • Built to mil-spec dimensions to avoid any weird gas issues.
  • Manufactured from mil-spec stainless steel.
  • Nitride finished for additional corrosion resistance and longer lifespan.
  • Black finish looks cool.


  • No roll pin included.

6. Spikes Tactical AR-15 Gas Tube - High Durability 300 Blackout Gas Tube

The Spikes Tactical AR-15 Gas Tube has been one of my go-to gas tubes for a while now. It’s relatively affordable. And it’s got a few noticeable upgrades over a standard mil-spec gas tube.

In terms of construction and dimensions, it’s a fairly standard gas tube. It’s manufactured from stainless steel, just like a mil-spec gas tube. And the dimensions match the mil-spec dimensions.

There’s only one difference between this and a mil-spec gas tube: the roll pin notch is ever so slightly deeper than a mil-spec gas tube. This makes it easier to punch your roll pin into place and minimizes the chances of damaging your gas tube during installation.

But, it makes no difference in your rifle’s operation. It works great.

Additionally, this gas tube is finished in black melonite. And it’s a respectably thick finish. The finish is quite corrosion and wear resistant.

The finish also withstands heat very wellIf you do a lot of rapid fire shooting, this gas tube has the durability you need.

Lastly, this Spikes Tactical gas tube is offered in all the different gas system lengthsWhatever size gas system you have, you can get this gas tube to fit.

Overall, this is an excellent option for anyone who runs their gun hard and needs components that can keep up.


  • Manufactured from mil-spec stainless steel to mil-spec dimensions for a perfect fit.
  • Roll pin notch is very slightly deeper to make installation easier and reduce the risk of gas tube damage when you install the roll pin.
  • Black melonite finish gives your gas tube better corrosion and heat resistance.
  • Includes a roll pin.
  • Black finish looks awesome.


  • Kind of expensive (for a gas tube).

Get Some Gas

In most AR style rifles you can just get any standard gas block and gas tube. It rarely causes gas system issues.

But 300 Blackout requires a bit more attention to the components you use to build your gas system. That way you get a properly functioning rifle without any tinkering.

If you want a reliable 300 Blackout gas system without paying TOO much attention, just get these two components:

  1. SLR GB7 .750 Non-Adjustable Micro Gas Block.
  2. ODIN Works Gas Tubes.

These two parts will give you a reliable gas system, and won’t cause too much overgassing if you run a suppressor.

Now that you know, it’s time to stop messing with your gas system and get to shooting. Get some good gas system components and get out of the gas system rut. That way you can actually shoot your 300 AAC rifle.

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