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WarBlock 75 High T-4

WarBlock 75 High T-4


Stand-alone WarBlock High T-4. Comes with gas tube roll pin and two 2/0 taper pins. Must be pinned into barrel by qualified user. For pinning options or pinned barrel assemblies please see the WarBlock Pinned Barrel Assemblies section above in the drop down menu under the products tab.

***We highly advise against pinning these yourself unless properly qualified. If you would like a Warblock already pinned on a barrel, we offer this service on customer supplied barrels as well as barrel assemblies. We can also get virtually any barrel you wish from our vendors. See products tab for options or contact us for details***

Out of stock

SKU: HT-4-75-SB Category: Tags: , , , , , , , , , , , , , , , , , , , , , , , ,


Precision machined from a solid billet of heat treated 4140 alloy steel this device 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. Upon firing, this 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 variety of rail mounted flip-up or detachable front sights. The advantage being that the front sight can be flipped to the down position or completely removed so as not to occlude the field of view when using an optical aiming device.

There are many different flip-up 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 has 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 flip-up sights have been used so that they may be in the down position when not in use and thus providing a clear view through the optic. This is the primary benefit of using this device.

Traditionally these flip-up 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 and ever so slightly warping and 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 shifts 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. Since this device 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 arraignment 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 we have precisely measured a 0.0025″ upward forearm rail deflection in relation to the barrel when the rifle’s own weight is supported by the free floated forearm rail. In other words that is about 2/3 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.

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 this device, no forearm rail space in consumed at all and thus it maximizes free rail space.

Another benefit when using this device 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.

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 this device and would like to retain the capabilities of the standard position sling swivel.

This 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 problems. Although it 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 is designed to be light weight 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 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.



********3/5/2015 The issue with the potential gas port occlusion has been resolved and is no longer an issue. An minor internal modification has been made to allow more clearance for the gas port when using a hand guard cap. All WarBlocks will be completely compatible with or without using a hand guard cap or hand guard cap spacing. As a matter of principle we will install WarBlocks with hand guard cap spacing unless otherwise requested. This is so that the user can opt to install a hand guard cap retroactively for use with standard hand guards.

********2/27/2015 We have secured a dealership with Faxon Firearms and can now offer you their excellent line of barrels in addition to CMMG.********

********2/27/2015 We have not received any complaints at all but due to a very minor and unforeseen tolerance issue recently discovered we advise not to use a hand guard cap or hand guard cap spacing with your install. Doing so will likely not cause any problems but there is the potential for partial gas port occlusion. This issue will be resolved on future WarBlocks but as a precaution we recommend installing the WarBlock while it is fully seated against the barrel shoulder without leaving any gap. We are also temporarily no longer offering the current barrel assemblies with hand guard caps or hand guard cap spacing. Very sorry of any inconveniences, the issue will be resolved soon. If you experience any short-stroking with your current WarBlock install please contact us so that we can fix it ASAP.********

********1/28/15 The production WarBlocks have returned from nitriding and orders are now open! Just a reminder this is the stand-alone gasblock which must be properly pinned into your un-pinned barrel by a qualified user. If you don’t know how to do it, you shouldn’t attempt it. For WarBlock pinned barrels or pinning customer supplied barrels see the WarBlock Pinned Barrel Assemblies section in the drop down menu under the Products tab. The WarBlock pinned barrels will be offered initially as a made to order item to accommodate different configurations and low stock quantities. We are a CMMG dealer so can get any of their barrels if you want a WarBlock pinned barrel that is not listed in the product section yet. If you do not see exactly what you want or have questions please contact us via email. Please bear with us as the site is being updated and product photos shot. The pre-release price of the WarBlock will be for a limited time.********

********1/5/15 Production has concluded on Sunday 1/4/15. We are verifying tolerances and fitment, and they will be set for salt bath nitriding tomorrow. Looking at opening orders for stand-alones next week and WarBlock pinned barrels shortly thereafter!********

********12/24/14 Production of the gasblock began on 12/16/14 and is currently underway. A name was chosen with a nomenclature that reflects the specs of the gasblock. It is a high rail gasblock with 4 t-slots designed for 0.750 journal AR15 barrels. It has a reinforced bayonet lug and sling swivel socket to accept 3/8″ sling swivel studs as standard features. More info to follow after the initial production run is complete.********

********11/14/14 We have the first samples back from nitriding. There are some cosmetic defects that arose from the nitriding process and will be fixed in all subsequent gasbocks. This defect does not affect the gasblocks function so they will be available for sale immediately at an even deeper discount than the pre-release price. These can be had for $65 which is less than half of the anticipated retail price but they won’t be posted for sale on the website. If you would like one for an insanely good deal either by itself of pinned on a barrel please contact us. Customers who email us to buy a blem will also get a 15% off coupon on your next order. These will be the very first ones made for sale.********

********11/7/14 This gasblock is about to be ready for sale. The final price has yet to be determined but customers who wish to purchase one at what will likely be a heavily discounted price may do so for the time being. There will be a very finite quantity available for immediate shipping at this price but placing an order during this time will guarantee you will receive one. This will be a pre-release sale which means that while the product fulfills all of its advertised design goals, certain manufacturing modifications may yet be made to further refine or enhance the product, primarily as it pertains to tolerances and cosmetics. Also shipping times cannot be guaranteed as we may have to do another run of them to honor all pre-release orders. However as a good faith gesture to earn your business the price will be lower and shipping in the CONUS will be free for orders placed during the pre-release sale period. The sale period is subject to end at any time. If unhappy in any way a refund or replacement will be offered. If you like the gasblock please help us get the word out and consider writing or doing a video review so we can tool up for more production runs! We also encourage any and all feedback to help us further improve our products as well as product suggestions. I know a lot of people have been waiting for this to be available and finally it’s almost here! There will be new images added to the blog and to this page soon. Once we verify the parts from finishing we will open up for orders. Thank you for your support!*********

********11/6/14 Initial orders placed for this gasblock will be for the gasblock by itself or for a new barrel with the gasblock pinned in. This means that if you have the tools and the know how you may purchase the standalone gasblock and pin it into your barrel of choice. If you do not wish to do that you may purchase one already pinned onto a new barrel from CMMG. As we become dealers for other manufacturers their brand barrels will be offered as well. Of course you may contact us with any questions or special order requests. Please bear with us as we update the site to reflect the product format. Early on it may be better to just contact us about orders until the site is updated.*********

Got something to discuss?

9 years 3 months ago

Thanks Pat! It’s been a ton of hard work but it’s getting there. I estimate they will be for sale in the next couple of weeks. They are currently in production and are turning out amazing although at a slow rate. This design has a lot of 3D machined features. Each gasblock gets more than an hour of continuous machine time as every surface is precision machined.
Yes, they will use MIL-STD taper pins as they are the strongest and most robust option plus they have the benefit of wedging the gas port of the gasblock even tighter against the gas port of the barrel for a better gas seal. This of course creates a dilemma to the end user as this method is not the easiest thing to do especially compared to the ease of set screws. To address this they will be offered as stand-alone gasblocks to those who wish to install them on their own with the proper tools and know-how (i.e. I have heard from a few military armorers wanting these as stand-alones). However they will also be offered already properly pinned on barrels and we have a fixture to do this. We will also accept new customer supplied barrels for WarBlock pinning or barrels that have not been previously pinned.
As for the material we’re not considering aluminum as it would not be robust enough especially with a finctional bayonet lug. The other issue is with thermal expansion coefficients. As the temperature rises aluminum expands at a higher rate than steel and could cause a gas port leak when the aluminum gasblock expands faster than the barrel. This of course causing under-gassing, short-stroking, and other reliability issues that we would like to completely avoid. Also concerning would be gas port erosion in aluminum with heavy use. Despite the current material being hardened 4140 steel it is still lighter weight than the standard front sight base thanks to all of the lightening measures built in. Even the addition of a Magpul BUIS still gets you a net weight reduction over just the plain FSB. A Troy BUIS on the other hand would result in a very slight weight gain over the FSB. There are two other materials that may be considered in the future: stainless steel (maybe 17-4 ph) simply for cosmetics (the nitriding already makes the 4140 ones virtually impervious to corrosion) and grade 5 6Al-4V titanium simply for ultimate weight reduction. Either one of those options would sky rocket the cost though, especially the Ti.

3 years 9 months ago

My AR currently has the standard A2 fsb. Would this gas block be able to fit and be pinned using the same notches in the barrel that held that A2 fsb in place?

3 years 9 months ago

Yes it can be done and some gunsmiths do it but we don’t pin barrels that have already been pinned here anymore. It’s too costly and time consuming to do for us, you can read more about why in the FAQ page.

3 years 3 months ago

Will this replace a flat top gas block? It is stamped with an F.

3 years 3 months ago

Hi Michael, the WarBlock rail is the same plane as the flat top receiver rail so in a sense the F marking doesn’t matter. That is a designation for FSB height. By being on the same plane, virtually any set of front and rear sights designed to work in conjunction with each other, will work with the WarBlock and a flat top receiver.