Bullpups seem to get short shrift with American shooting sports enthusiasts, which is interesting, considering the features they have to offer. Bullpups are among the most compact semi-automatic carbines available. Models such as the IWI X95, Springfield Hellion, Steyr AUG A3 M1 and the Desert Tech WLVRN commonly sport an overall length between 26″ to 28″ with carbine-length barrels. This is possible because the action has been moved back behind the trigger instead of above the trigger like most carbines in this class. The bullpup configuration shifts much of the gun’s weight back near the shoulder. This, in turn, can imbue the gun with quick handling and a well-balanced feel. If bullpups are compact, well-balanced and available from trusted manufacturers, then what’s not to like?
Although bullpups have been more widely adopted by armies, agencies and individuals overseas, here in the United States, the impressively modular AR-15, or modern sporting rifle (MSR) if you prefer, is currently king. Yes, an AR with a typical fixed or adjustable stock is going to be longer than a bullpup. However, components are diverse and plentiful, the guns can be modified and customized in a variety of ways and caliber conversions are a snap. Remove the magazine and the upper from the lower receiver and then install a different upper and magazine. In less than a minute, your AR carbine or rifle can go from being chambered in 5.56 NATO/.223 Rem. to a number of other calibers including .300 BLK, .350 Legend or .450 Bushmaster, just to name a few. ARs can be outfitted with excellent aftermarket trigger upgrades, while bullpups have garnered a reputation for relatively heavy triggers.
But what if there was an option available which blended features from the compact configuration of a bullpup with the modularity of the AR-15? And what if that option was an accessory that could be ordered and shipped directly to you without the need for an FFL transfer? And wouldn’t it be convenient if it could be paired with an upper, or uppers, you already own?
This is just what A3 Industries provides with its Triad Modular Bullpup Chassis system. I’ve worked with some unusual and innovative AR-15 lowers in the past, so this system certainly piqued my interest. Here is a closer look at the system and how it performed when configured for a Brownells BRN-180 Gen 2 upper.
Pick A Stripped Mil-Spec Lower
The Triad chassis, like many other rifle chassis systems, is not a serial-numbered component. Instead, it’s designed to house an AR-15 type, mil-spec stripped lower receiver. Since the lower is the serial numbered component, it will need to be acquired through an FFL dealer, unless you happen to have one squirreled away for a rainy day. Stick with a forged lower without a trigger guard, and you should be good to go.
For this project, I checked in with the Aero Precision team, who kindly sent out one of their mil-spec Gen 2 lowers (#APAR501101C; $135) to include in this evaluation. It should be noted here that, if you are starting with a completely bare receiver, that most of the parts needed for the lower will be provided in the Triad Kit. But for reasons that elude me, they do not provide the left-side bolt catch lever assembly in the hardware kit. If you need one, it has to be purchased separately.
The Triad Chassis
A3 Industries offers two versions of the Triad chassis. The all-aluminum version (#TBC-A) with hardware is available for $699.95 when purchased directly from the company website. For this evaluation, I worked with the aluminum and polymer version of the kit (TBC-P), which is listed for $399.95.
The forward portion of the chassis, which is the first trigger housing block, is milled from 6061 aluminum and treated with a hardcoat anodized finish. At the top front edge is a third pin addition to the takedown and pivot pins. It attaches to a mount that is installed into an M-Lok slot in the handguard for added support.
The generously oversized integral trigger guard protects the curved 7075 aluminum forward trigger. This trigger is connected to an adjustable linkage, or actuator, which cycles the second trigger of the drop-in fire control group that is installed in the mil-spec lower receiver. The other forward features include an ambidextrous aluminum safety selector and a removable in-house AR-15 style A3 XENO-patterned reduced angle polymer pistol grip.
The rear of the chassis is injection-molded from 30 percent glass-reinforced Zytel polymer. The controls, supports and threaded chassis inserts are made from 4140 steel or 7075 aluminum. The polymer portion houses the AR-15 lower along with the pivot and takedown pins. The controls and features include the beveled magazine well, the bolt catch lever, left and right side magazine release buttons, two QD sling ports, a 2″ long polymer extension block, if needed, and a textured soft rubber butt pad.
On the left side, behind the magazine button, is a service port. It provides access to adjust the rear linkage for proper contact with the second trigger. Another set of ports is provided for those who would like to install a second mil-spec safety selector lever, left side only or ambidextrous, directly into the lower receiver. In this case, I opted for the forward safety selector only and installed the provided filler plates.
Choose Your Upper & Layout
Because the Triad chassis is designed to operate without a rear buffer assembly, it is only compatible with those AR uppers which employ recoil assemblies housed inside of the upper receiver. As of this writing, A3 Industries offer kits configured for the Matador Arms MAT-9, Palmetto State Armory JAKL, Foxtrot Mike Products FM-15 and the Brownells BRN-180 Gen 2 and Gen 3 series of factory produced upper receiver assemblies.
After selecting an aluminum or polymer chassis, customers will need to select the correct parts kits for their upper. Available for AR rifles or pistols, the hardware sets vary in price, from $129.95 to $169.95, depending on the model selected. The rifle kits include a rubber butt pad for shouldering the gun while the pistol kits ship with a QD ported end cap. For this evaluation, I requested the BRN-180 compatible rifle kit which was $159.95.
A Note About Overall Length
Among the components included with the Triad kit is a 2″ long polymer extension block that fits in between the chassis and the butt pad. Whether or not you’ll need to install this block depends on the length of the upper assembly’s barrel. Current U.S. regulations state that a shoulder-fired rifle must have a barrel that is at least 16″ long and an overall length of no less than 26″. If either the barrel or the overall length is shorter than required, then the gun is classified as a Short Barrel Rifle (SBR) and must undergo the registration process specified in NFA regulations. Failure to do so is a felony.
In order to ensure the carbine being assembled was not an NFA item, I did some careful measuring of the equipment on hand before installing an upper. With the 2″ extension block installed, the carbine would have an overall length of 26.25″ with a 16″ barrel BRN-180 Gen 2 upper in place. In the photos, I included a BRN-180 Gen 1 upper with an 18.5″ barrel for comparison. Unfortunately the Gen 1 was not compatible with the Triad system. But if it had fit, then the carbine’s overall length would have been 26.75″ without the extension.
Here are a few things to keep in mind. First, overall length is measured from the muzzle of the barrel or from the tip of a permanently attached muzzle device. A removable muzzle device is not counted as part of the overall length. Secondly, do not just assume that your kit and upper are going to come together at a just-right length. Measure and measure again! If you have any questions or concerns, check in with A3 Industries before completing the assembly of your rifle. Finally, if you are going to be switching barrel lengths, make sure all of the uppers used meet or exceed the 26″ minimum overall length when installed.
Some Assembly Required
My use of the word “some” in the section heading is a bit tongue-in-cheek. In fact, the installation of a stripped lower into the Triad chassis is a relatively technical and detailed process involving several small parts. A3 Industries provides a useful set of instruction manuals in PDF format which can be printed or viewed online. I would say the assembly process is on par in complexity with building a complete AR-15 from a box of parts. However, no specialized tools are required and several hex wrenches are provided in the parts kit.
The assembly of the chassis system is something that will be enjoyable to gear heads (like me) who enjoy this sort of thing. But don’t try to do it in a hurry. Clear your workbench, lay out the parts and read through the instructions first. Then grab a cold drink and fire up the radio while relaxing into an hour or two of assembly. Don’t forget to run a complete set of bench checks with the upper installed and an empty magazine once the build is complete.
With the Triad chassis fully assembled, I had two piston-operated BRN-180 Gen 2 16″ barrel uppers on hand to work with. One was chambered in .350 Legend, which received a solid workout in this review. The other was a .223 Wylde model fitted with a replica of a three-prong AR-180 flash hider. I had yet to shoot this upper, so it was put to work with the Triad.
Once it was all put together, it was good to see that the overall quality, fit and finish of the Triad chassis was in line with that of the Brownells upper. In other words, it did not have the “Frankengun” look that mixing AR components sometimes produces. Sans optic, magazine and ammunition, the finished carbine tipped the scales at 7 lbs., 9.4 ozs. Since the average AR-15 carbine weighs in at around 6 to 7 lbs., this particular assemblage is not a lightweight but not excessively heavy either.
If there is one feature that was going to make or break the kit, it would be the qualities of the trigger. Some bullpup linkage systems have been known to produce heavy, gritty, indistinctive and generally unpleasant triggers to work with. That was not the case here. The trigger was unmistakably single-stage. Free of any creep, it broke cleanly and smoothly with 4 lbs., 7 ozs. of trigger pull. Although this is not the lightest AR trigger pull available, I was impressed by how much it felt like a typical AR trigger, not a linkage system. Blindfolded, I would not have known the difference.
At The Shooting Range
For the range evaluation, this carbine was topped off with EOTECH’s recently released VUDU 3-9X 32 mm Super-Short rifle scope. I’m not going to say much about it here because we’ll be posting a full review of this optic (stay tuned). But it was a terrific fit for this carbine.
The standard capacity 30-round magazines used for the test included a Brownells aluminum mil-spec box along with polymer models from Elite Tactical Systems (ETS), Magpul and Mission First Tactical (MFT). These magazines, along with all of the ammunition tested, functioned flawlessly. There were no gun-, magazine- or ammunition-related issues throughout the course of fire.
Formal bench rested accuracy testing was conducted by firing five, five-shot group into paper targets posted at a distance of 100 yards. The rounds fired included Federal Fusion hunting, Gorilla Ammunition launching Sierra Bullets Matchking open-tip projectiles and Winchester USA practice-grade loads. A Garmin Xero C1 Pro chronograph was used to track bullet velocity averages for 10-shot strings. Here are the results:
Parting Shots
A3 Industries’ Triad Chassis system provides a handy, reliable and more affordable way for AR fans to try a bullpup platform on for size. The dedicated bullpups mentioned earlier list for real world prices between $1,750 to $2,500. As configured, the Triad chassis and BRN-180 combo tested here runs about $1,600 if we throw in a $15 magazine. But that’s if all the parts are purchased new. For those who already have compatible uppers and stripped lowers on hand, the price will be less than $600.
As for me, the Triad chassis left me wanting more. This bullpup fits me and shooting preferences quite nicely. I’m eager to swap out the .223 Wylde upper for the .350 Legend version and see how it performs as a compact, multi-purpose rifle. Or, how about starting over with a Triad pistol kit paired with Brownells BRN-180 Gen 9″ barrel pistol upper chambered in.300 BLK outfitted with one of Silencer Central’s lightweight titanium suppressors? That could be quite interesting as well. I’m looking forward to what we can come up with next. For more information about the Triad system, visit a3industries.com.
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