Why WarBlock?


modelsWarBlock designator


Precision machined from a solid billet of hardened 4140 alloy steel the WarBlock (Patent Pending) receiver level railed gas block is a true problem solver. This 4oz. piece of finely CNC sculpted steel replaces the front sight base of the M16/AR-15 series rifle and serves the same function in terms of the direct impingement gas system, but it also reverses decades of a flawed trend in the AR community. Intrigued? Read on.




Upon firing, the direct impingement gas system re-directs high pressure gas from the barrel back into the action of the weapon causing the bolt carrier group to cycle and allows for automatic or semi-automatic fire. The main difference is that instead of having a fixed front sight, as is standard, a MIL-STD-1913 Picatinny rail that is placed at the same level as the receiver rail is used. This allows for the mounting of a wide variety of rail mounted folding or detachable front sights. The advantage being that the front sight can be folded to the down position or completely removed so as not to occlude the field of view when using an optical aiming device, when a lower profile fore end signature is desired, or just when a cleaner and less “busy” sight picture enhances the shooters target acquisition as well as potentially making threats more visible by not obscuring them in your field of view.

reticle with buis up bothreticle with buis down both



Some railed gas blocks are referred to as “gas block” height (image left) and are lower than the receiver rail plane. These have a few major disadvantages, namely that unless one uses an unnecessarily tall, bulky, and option limited gas block height front sight (image right), you cannot use the ubiquitous standard “same plane” iron sight as they wouldn’t even register with your rear iron sight at all. Consequently they never really caught on and as a result there are very few back up iron sights (BUIS) designed for this height gas block on the market and even the continued existence of this height standard is questionable.


Making far more sense is the advent of the receiver level railed gas block, also called receiver height, or same plane railed gas block, which allows the use of a myriad of front sight options designed for forearm rail mounting.

Same Plane WarBlock 75 Picatinney railed gas block
Same Plane WarBlock 75 Picatinny railed gas block

There are many different folding and detachable front sight designs, but the majority of them have a commonality, and that is the height at which they mount to the host weapon relative to the axis of the bore. This is due to the fact that the rear sight is a standard height, even when mounted to the receiver rail and not of a fixed design. Forearm rails, including free-floating designs which do not contact the barrel, are a relatively recent upgrade and allow for the mounting of various accessories such as lasers and flashlights to the weapon. In addition to this, the recent wide-spread adoption of optical aiming devices has presented a unique problem. The standard front sight base occludes the field of view when using the optic. As a remedy for this problem, various folding sights have been used so that they may be in the down position when not in use and thus providing a clear field of view through the optic.

Fantasy Zero

WarBlock 75WarBlock 75 Traditionally these folding sights were designed to be mounted to the forearm rail which is at the same level above the axis of the bore as the receiver rail. Unfortunately, this arrangement has resulted in another unique problem. Since free-floating forearm rails are not directly attached to the barrel, and the flip-up front sights attach to this rail, then the sight is not “hard mounted” to the barrel. This causes a phenomenon known as “point of impact drift” and is caused by the barrel heating up during firing, becoming more elastic, and ever so slightly warping or drooping as any stresses in the metal are being temporarily relieved, causing the point of impact to progressively change relative to the point of aim. Normally this is a non-issue because the standard fixed front sight base is directly attached to the barrel, so as the barrel warps and the point of impact drifts so does the point of aim, which exactly follows. However, when the front sight is mounted to the forearm rail which has no direct relationship to the barrel, the barrel will warp independently of the rail and front sight, causing discrepancies between the point of aim and the point of impact of the bullet. We call this having a floating zero, or fantasy zero. That is a zero that is only valid under the best case scenario. Since the WarBlock mounts directly to the barrel in the same way as the standard front sight base, and the front sight mounts directly to that, then there will be no discrepancies and thus the problem of point of impact drift is eliminated. This mounting arrangement has the added benefit of much more rigidly securing the front sight to the barrel so that any tensions or stresses put upon the forearm rail, whether it be from the sling pulling to one side of the rail or resting the rail on a barrier inducing upwards flex, will have no effect on the barrel or sight. In fact approximately 0.0025″ of upward forearm rail deflection in relation to the barrel is typical when the rifle’s own weight is supported by the free floated forearm rail, and this test was with the best case scenario carbine length rail that is both shorter and more rigid than longer rails. In other words that is about a minimum 1 MOA shift from just from setting the rifle on a rest or even supporting it by hand, anything beyond that including heavier barrels, suppressors, or longer rails, will simply make it that much worse. Additionally barrel mounting the front sight insulates it to some extent protecting it from potential rail misalignment occurring from a sudden impact such as a drop or hitting the rail against a barrier, which would certainly ruin the zero of the back up sight if mounted directly to the rail.


A topic not often brought up because it hasn’t been an issue with the standard front sight base, is that of the material selection. The standard front sight base is made of steel for many reasons including durability, but also its thermal loading characteristics. All barrels are made of steel and steel expands at a predictable rate as its temperature rises. In the case of AR15 barrels made of either 4140CM or 4150CMV the thermal expansion coefficient is approximately 7.2″ x 10^-6 per 1°F rise in temperature. Meaning that the diameter of the barrel is expanding as it is heating up from firing. Given that the gas block of an AR15 is essentially a gas seal containing gas pressures approaching as high as 65,000psi, being necessary for the weapon to function, and both the barrel and gas block can get quite hot attaining temperatures of up to 1500°F with sustained fire, it follows that the material chosen for the gas block should have approximately the same thermal coefficient as the barrel to which it is attached. Despite this there are some railed gas blocks that do mount directly to the barrel but in an effort to reduce manufacturing complexity and still be somewhat lightweight they are made of aluminum. Aluminum has nearly double the thermal expansion coefficient of steel at about 13″ x 10^-6 per 1°F rise in temperature. This means that an aluminum gas block expands at nearly double the rate as the underlying steel barrel when heating up from firing, making a gas leak and weapon failure much more likely. Additionally the melting point of aluminum is 1221°F vs. 2600°F for steel, revealing even the possibility of melting an aluminum gas block. As unlikely as it sounds this occurrence has been confirmed to us by a well known barrel manufacturer during barrel testing. For all of these reasons the WarBlock is meticulously sculpted out of solid bars of high quality 4140 heat treated steel alloy, designed for extreme durability from all elements of abuse including securing a bayonet, and yet still be extremely lightweight. This was achieved through finite element analysis consultation during the design process as well as mimicking the famous industrial technique for creating the perfect combination of strength and low weight, the I-beam.

WarBlock FEAt


The WarBlock also has another distinct advantage over other railed gas blocks that may at first glance seem inconvenient, and that is its attachment method to the barrel. Unlike the vast majority of other products, the WarBlock has retained the original and ubiquitous mounting method of the standard front sight base. While this may potentially be more involved initially due to it being a procedure best left to qualified persons to perform, the performance benefits far outweigh any minor inconveniences real or imagined. Pinning the WarBlock to the barrel produces the most rigid and stable mounting that can be achieved short of welding them together. Being that the WarBlock has a receiver level rail, also sometimes referred to as a “high rail”, there is a larger leverage effect from forces applied to it that can torque a non-pinned gas block out of alignment much more easily. Gas blocks shifting out of alignment not only compromise the reliability of the weapon by occluding the gas port, but a gas block with a BUIS will also become useless as the zero will be grossly lost. Any gas block that may be subjected to abuse in a hostile environment such as from impact forces should therefore be pinned. Of course since the WarBlock comes standard with a bayonet lug this certainly qualifies if for being exposed to impact forces. If a gas block is to have a functional bayonet lug, it also should be pinned. Using MIL-STD 2/0 taper pins, as is intended with the WarBlock, has yet another silver lining. The taper pin holes, when done correctly, should leave half-circle cut-outs on the underside of the barrel such that the pins are bisected by the barrel’s tangency. When the pins are driven in they act as a wedge to drive the gas block down hard into the top of the barrel creating as tight of a gas seal as possible and ensuring the ultimate reliability in the weapon.

WarBlock 75 Series Pin Locationsproperly pinned ar15 barrelstripped WarBlock pinned barrel


Rail Estate

With the advent of a multitude of accessories such as high intensity flashlights, lasers, vertical grips, and bipods being mounted to the host weapon to increase its adaptability, rail space becomes a concern. When using a flip-up front sight mounted to the forearm rail, a full 2.5 inches of valuable rail space can be consumed. This is especially important when an infrared laser aiming module is attached, as they are typically mounted on the top forearm rail in this area. However, when mounting a flip-up front sight to the WarBlock, no forearm rail space is consumed at all and thus it maximizes free rail space.


Sight Radius

Another benefit gained when using the WarBlock is that a front sight that is mounted to it will be farther away from the rear sight than it would be when mounted to the forearm rail. This preserves the sight radius of the standard fixed front sight base and allows for no degradation in precision as is suffered when reducing the distance between the front and rear sights.

Sling Point Versatility

Along with a standard bayonet lug, another feature designed into this gas block is a female socket to accept a quick attach/detach sling swivel. This is for users who would like the option to remove or attach the sling quickly, interchangeably use in conjunction with a side mounted forearm rail socket mount, or for those who do not wish to use a forearm rail but still desire the benefits of the WarBlock and would like to retain the capabilities of the standard position sling swivel. The sling swivel socket also has a built in rotation limiter that prevents the sling from rotating more than 90 degrees or 1/4 rotation and becoming tangled.


Weight and Finish



The WarBlock receiver level railed gas block offers all of the advantages of the standard fixed front sight base and the forearm rail mounted flip-up front sight and none of the disadvantages. Although The WarBlock is made of heat treated 4140 alloy steel, the same or similar to the barrel and thus suffers no issues with thermal expansion discrepancies, it’s designed to be lightweight and have a near zero sum weight difference over the standard fixed front sight base and potentially a net weight reduction depending on the front sight chosen to be mounted. The standard WarBlock 75 High T-4 weighs in at an incredible 4oz. making it almost 30{bf1535d22b332f69d7a2d53a4e01e5867624aab1b456f60c0cd75d6084bc173a} lighter than a standard front sight base. The finish is a beautiful ultra-hard and corrosion resistant high performance salt bath nitride treatment, also known as Meloniting, that ultimately makes the WarBlock’s surface nearly indestructible.



In addition to the standard 0.750″ bore WarBlock or WarBlock 75 High T-4 designation, we also have the the WarBlock 58 (five-eight, shown below) that has been redesigned from the ground up to accommodate 0.625″ pencil barrels. The WarBlock 58 draws its lineage from the WarBlock 75 and has all of the same features but has been shrunk down in all the right places to make it as purpose built, lightweight, and streamlined as possible. The WarBlock 58 weighs in at only 4.3oz..

75 and 58

Expanding upon the evolution of the WarBlock line, a new model has been introduced that omits the bayonet lug. We understand not everyone needs or even wants this device, especially hunters, 3-gun competitors, and target shooters, all looking to save weight. Some even live in restrictive states that don’t allow bayonet lugs on rifles. Shaving off half an ounce in weight and weighing in at only 3.5oz. is the WarBlock LiteHunter

WarBlock 75 LiteHunter


In summary the WarBlock is the best, strongest, sleekest, and lightest receiver height Picatinny railed AR15 gas block on the market today combining all of just the right features not found in any other product.

-Receiver level same plane Picatinny railed gas block compatible with all of the receiver height flip-up back-up iron sights. Not the increasingly antiquated “gas block” height rail.

-Utilizes the tried and true direct impingement gas system but yet is still compatible with and a perfect option for piston retrofit kits.

-Precision machined from high quality 4140HT alloy steel, the same or nearly the same as most AR15 barrels. Not aluminum.

-Has a real functional bayonet lug. Not just a decorative afterthought.

-Uses the most rock solid secure mounting method of MIL-STD 2/0 tapers pins. Not set screws or clamps.

-Modernizes the concept of the sling attachment point by integrating a QD sling swivel socket with rotation limiter. Not just a rivet.

-Beautifully sculpted to reflect the traditional contours of the AR15 but with the modern business end functionality of the A3 and A4 flattop receiver. Not just a box with a hole and a rail.

-Weighs in at only 4oz. as all non-critical mass is machined away making it nearly 30{bf1535d22b332f69d7a2d53a4e01e5867624aab1b456f60c0cd75d6084bc173a} lighter than a standard front sight base.

-Has a rich ultra-hard, corrosion resistant, and nearly indestructible QPQ salt bath nitrided finish (also called Melonite).


How to buy

In addition to this resulting perfect blend of features, having the pinning service done right here onto to any barrel purchased through us, like the excellent barrels made by Faxon Firearms, is FREE. Should you already have a barrel or have a different barrel in mind, virtually any virgin barrel that you send us can be pinned for a small fee, presenting you with the ultimate in value, versatility, convenience, and performance. From the most discerning AR15 to the hardest duty M16, the WarBlock represents a phase shift in the evolution of the platform that all keen observers of the black rifle will recognize and appreciate.

Because the WarBlock series is affixed to the barrel using taper pins that must be skillfully aligned, drilled, and reamed, this is not an easily user installable upgrade. Consequently, and for your convenience, we offer the WarBlock series in conjunction with the barrel pinning service on your customer supplied barrel, our fine line of Faxon barrels, or as complete or stripped uppers, but generally do not offer the stand-alone WarBlocks themselves anymore. However if you wish to purchase the stand-alone WarBlock for pinning yourself, just contact us and we will make it available to you.

The newest ways we are rolling out WarBlock equipped barrels and uppers is to have you build them yourself, that is to virtually build them using our free interactive web apps, the WarBlock Barrel Builder and the WarBlock Upper Builder. The WarBlock Barrel Builder allows you to configure your barrel assembly with different barrels and components to your specifications while getting a real time visual representation of the in-process build. The WarBlock Upper Builder takes it a step further and allows you to configure a complete upper built around WarBlock barreled uppers. You can even add a charging handle, bolt carrier group, and iron sights, all in a photo-realistic environment, giving you an image of exactly what your build will look like. You can also play around with different configurations to help decide on what you want. Once ordered, with any special notes added, we will then build your order for real, configured exactly the way you want it and shipped to your door. Click one of the images below to visit our WarBlock Barrel Builder or WarBlock Upper Builder web apps to get started building your own custom WarBlock blaster today, the way you want it. Join the WarBlock Army.


WarBlock Barrel Builder web app          warblock-upper-builder-icon-large




Join the Conversation

  1. James Dressman


  1. I love the way your gas block is turning out so far. If I see the picture right you are going to use the factory taper pin for mounting. That is a good way to go. Also have you thought of using aircraft grade aluminum like T6 or greater to make them even lighter just a thought.

  2. James,
    One more question for you, what if I wanted one of your gas blocks in the raw unfinished form right off the mill, no sand blasting and or parker finish?

  3. I could not be happier with the WarBlock. The design is excellent and the machining is impeccable. A lot of love went into this design! Probably a lot of blood, sweat and tears, too. I ordered a second WarBlock pinned to the equally excellent CMMG barrel for my next AR build project.

  4. I have a Colt M4 Carbine. I would like to purchase the gas block by itself and have it installed by a local gunsmith. Please let me know if this is possible.

    1. Hi Jordan,
      We can make a stand-alone WarBlock available to you for gunsmith installation. One thing to note is that installing a WarBlock onto a barrel that has already been pinned is difficult so just be sure your gunsmith is equipped for this and willing to do it. Email with direct link for purchase is inbound. Thanks

  5. Are there plans to offer the WarBlock LiteHunter in an adjustable version? If so, do you have an ETA you will share?
    Thank you.

    1. Hi Chris, yes there are plans to offer all of the WarBlock line an adjustable version. We do not have an ETA as of yet but I would caution that it will likely not be this year. Thank you and please check back periodically for updates or subscribe to our blog for further details.

  6. Is the LiteHunter available as the WarBlock 58 for a .625 barrel, and if not are there plans to be?
    Thank you,

    1. Hi Chris,
      Good question. It’s not available at this time but yes there are going to be some WarBlock 58 LiteHunters made as soon as we can fit them in a batch process. The only reason that they weren’t made in the last batch process was because we allocated all of the available raw materials to developing the other 2 new variants. The WarBlock 58 LiteHunter will happen but no estimates on when they will be available yet.

  7. Are there any clearance issues using the Magpul MOE SL handguards with the WarBlocks?
    Thank you,

    1. None whatsoever, we use those all the time. The only caveat is that you can’t use the built in QD sling swivel socket of the WarBlock with the SL.

  8. War Machine gets it. The WarBlock solves the biggest yet most ignored problem with AR platform. The design specification is an unequivocal answer to the dynamic nature of this component and system.

  9. Can I buy just the WarBlock for a .750″ barrel? I have a carbine on the way with a Pic rail upper and an A-frame front sight. The A-frame will go into the trash immediately. I’m wanting a same-plane base with lug and sling-swivel point– exactly like has the WarBlock. Can I buy only the WarBlock? Thanks…

    1. Yes the WarBlock itself can be made available for purchase by users who have the equipment, expertise, and desire to perform the pinning themselves. Please email us for details.

  10. I’d like to purchase a WarBlock75 for an existing build and install by my gunsmith. What does just the block itself cost and do you offer a LE/MIL discount? Thank you.

  11. Like Chris, I want a WarBlock 58 LiteHunter. I’ll keep checking back for release. Very cool that you accept Bitcoin. Can you put me on a notification list when the WarBlock 58 LiteHunter is released?

  12. Hi, the WarBlock 75 High is EXACTLY what I’ve been looking for. I have a DD M4A1 and the barrel will need to be reamed, as it came with only one cut for a slim gas block from DD, but I’d like to have my gunsmith install it locally.

  13. Was trying to use the “Barrel Builder” app to order the Faxon 16″ Pencil, Mid-Length with WarBlock 58 installed, but that option was not available. Can this combination be special-ordered? Does Faxon have any plans to offer the 16″ pencil in 1:12 twist? For my application, 1:12 works best. With the 58 Lite Hunter, it would be perfect. Appreciate your good work and nice website.

    1. Email inbound. We can’t offer the pencil barrel with the WarBlock because the gas block journal of the pencil barrel is too short for a full sized gas block like the WarBlock 58. However we do offer the GUNNER profile, which is a hybrid SOCOM profile rear of the hand guard cap and a pencil profile forward of it. The GUNNER profile has a longer journal and can accept full sized gas blocks.

    1. Hi Jonathan,

      Yes we have been planning to do this for some time but are postponing until we can dedicate enough time and resources to do it right.

  14. So when looking to purchase one of these blocks, I’m looking at a 75 High T-4. There is one that says standalone and one that doesn’t. What’s the difference here that I’m missing? Probably something simple and obvious but better to ask before dropping money to be sure.

    1. Hi Chris,

      The stand-alone WarBlock is just the WarBlock itself with 2 taper pins, a gas tube roll pin, and pin hole location sheet. These are for those who wish to pin the WarBlock into their barrel themselves. This option is not recommended for the average user. If you know how, have the tools, and wish to do the pinning yourself the the stand-alone is an option, otherwise please use the WarBlock Barrel builder or WarBlock Upper builder to order as these assume that we will do the pinning here. I hope that helps!

      1. If a barrel has already had an A2 F-Marked FSB pinned on it, will this be a direct swap between the two?

        1. Hi Chris,

          No, sorry directly swapping between two different pinned gas blocks is not really possible, there is no standard for the pin hole locations between manufacturers and they would be almost impossible to line up correctly. You can read more about that problem in the FAQ page

  15. So I have a barrel and I would like to have the .750 with the sling mount attached. How do I go about ordering, sending in my barrel, and having it pinned?

  16. Hi,

    I have a Smith and Wesson M&P 15 Sport 2, I have removed the front sight post that was pinned to the barrel. I noticed in an earlier comment that you stated it would be more difficult to now pin your gas block to my barrel because it has been previously pinned, but can it still be done? I do have a local gunsmith that I will take it to but just wanted to know what the difficulty will be.
    Also I am wanting the rail to be same height as exisisting rails on the weapon and with the bayonet lug and the sling adapter so can you please tell me which item to select?

    Thank you for your time,


    1. Hi Jeff,
      Yes you are correct, trying to pin a WarBlock to a barrel that already has pin holes is quite an ordeal. We have occasionally done it to try and develop a cost and time effective method but we are not there yet. We may offer it in the future as we can invest more in specialized tooling and equipment but for right now every one of these retro pins we have done has been a major loss in terms of time and broken tooling. You can read more about why it is so difficult in the FAQ page. Your gunsmith may have a way and in that case we would be happy to send you a stand-alone WarBlock and what you need to give to him, just make sure he is aware of how hard the nitrided surface is. Thanks and sorry we can’t do it yet.

    1. Hi Lee,

      Not at this time but we will in the future. I can add you to the notify list when these become available. Thank You.

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