Chad Wallace

April 12, 2025

Guns, Gear, review

SRU SARB-15 Bullpup Chassis

Chad Wallace

April 12, 2025

Guns, Gear, review

SRU Bullpup Chassis

Review

SRU Precision has brought out some pretty nice AR bullpup conversion kits. If you have been thinking about getting a bullpup, the SRU kit might be the way to go. The SRU AR15 bullpup chassis comes in a number of configurations to help you choose the right system for you.

To sum up the SRU Bullpup Chassis, it is a 2 piece shell that wraps around an AR15. Not the full AR, just a mil-spec receiver and an upper. There is a stipulation on the style, or type, of upper receiver you use. A standard one can be used, but you will need to get a short recoil system. If you do not want to go this route, any bufferless upper should work. These include the Jakl, BRN-180, or what I used, the Foxtrot Mike Gen 2. The 2 piece shell is made from a carbon fiber infused polymer, which gives it extra strength and rigidity.

Installation of the SRU chassis can be time consuming. There are a lot of screws and pieces that hold the SRU Chassis around the AR lower receiver. Using the Foxtrot Mike upper made it a little bit easier. Luckily SRU has some detailed online instructions. Let’s just say that this is not the easiest kit to assemble. First, you have to take out most of the SRU Chassis’ screws. Then you will have both sides apart to start putting in the parts. Next install the short buffer tube into your lower receiver with the proper parts for your chosen upper. Then install the lower receiver assembly into the chassis. Make sure you have removed the trigger guard from the bottom of your receiver, or the SRU chassis will not work. Adjust the trigger travel screw. The SRU chassis uses a trigger linkage, which is why it needs adjustment. There is also a QD forward mount that needs to be installed and adjusted. This forward mount holds the bottom of the upper receiver in-line with the chassis. Now you can reassemble the two halves. Trust me, I simplified this for the review. I probably had the chassis apart 3 or 4 times to get all the parts adjusted correctly.

The trigger system is what really makes the SRU Bullpup Chassis shine. Since the SRU kit uses an aluminum trigger linkage, you get a good trigger. Bullpups are notorious for having bad trigger pulls, but SRU seemed to solve this problem. Another advantage to the SRU kit is that you can choose any AR15 trigger to install. That is because the trigger is actually in your AR receiver at the rear of the bullpup. The SRU kit does add about 1 pound to the total trigger pull weight. I used a Black Talon Tactical 3.5 pound trigger and it ended up right at 4.5 pounds. SRU made the chassis with a flat trigger and a single sided safety. These are pretty decent. If you do not like them, you can change them out for any mil-spec trigger shoe or any AR safety that you like, including ambi ones. You can also take the triggers pre-travel out by shimming it, the instructions just don't explain how to keep the shim in place.

The SRU Chassis does not come with a pistol grip. This is not a big deal. I installed a Thril pistol grip because I like them. Even though it worked well, I soon realized that a more vertical grip would work much better. This is because there is not much room between the pistol grip and where the chassis drops down to accommodate the magazine, and the magazine itself. It is pretty minor, and I still have the Thril grip on it. I also found the length of pull to be long. SRU states 15.3 inches, which seems about right. If you have short arms, it might be harder to reach the trigger than with a standard AR.

I should probably mention a few differences when using the SRU chassis. The mag release comes to mind first. It uses a lever style behind the magazine, similar to an AK style. It works well for me, but it did take some getting used to. Another thing to note is that you may need a higher than usual optics mount. This is because your cheek rests on top of the receiver, on the little pic rail cover SRU supplies. First I mounted up a red dot. Then I went to the ZeroTech Thrive HD 1-8 in a standard cantilever mount with a riser. Lastly, a 1.93 Geissele mount was added. It put the scope up high enough to use without a riser.

Foxtrot Mike was kind enough to send me the upper for the SRU Bullpup. That way I could just drop in the upper and not have to worry about short stroke kits. The upper Foxtrot sent is their brand new monolithic style upper receiver. It uses their forward charging system and a built-in buffer/spring recoil system. This particular monolithic system uses a 1 piece barrel, gas block, and barrel extension. It also uses a 308 size bolt for more strength. The Foxtrot upper has a full 16 barrel and comes with a threaded on A2 flash hider. This system with the SRU chassis made a really nice bullpup. The barrel sticks out just far enough so that you do not feel like you are going to shoot your hand off.

Now it is time for the love-hate experience. Okay, more love than hate. I was not sure how I would like this bullpup in the beginning. It surprised me. I really like how compact it is. The forward charging upper with the SRU kit makes it easy to cycle with the gun up on your shoulder or while running the gun. Magazine changes are fairly quick, even if I can do an AR mag change faster. The whole thing weighs 7.25 pounds without a mag or optics. So it handled pretty decently for me. Plus the weight is toward the rear, so you are not trying to swing a heavy weight back and forth between targets. Since I did not shim the trigger, there is a bit of take up before you get to the trigger's break. I just did not want to take it apart again to shim the trigger. You will also notice in the pictures that the scope mount is turned around backwards. This was done on purpose so that the physical mount would not get in the way of the forward charging handle. You can turn it around to the normal position and it will work. I just didn’t like my hand rubbing on the mount.

If you like bullpups, or maybe just want to try one out, the SRU Bullpup Chassis kit may be a good fit. The quality of the kit is top notch. It probably has one of the best bullpup trigger systems around, at least in how it feels. The polymer chassis feels good and not cheap. I ended up really liking the SRU bullpup chassis. Head over to SRU and check it out.

Firearms Insider Reviews - Key Points

Claim to Fame:

Bullpup conversion for AR15 rifles

Target Market:

Anyone wanting a top quality bullpup

Features, Benefits, and Specifications of this product:

LOP: 15.3”
OAL with 16” barrel AR15: 26”-29”
Kit OAL: 20” (without handguard) / 25” (with handguard)
Weight: 980g (without handguard) / 1320g (with handguard)
Shell: PA66+CARBON FIBER injection molded
Trigger Linkage System: 6061 T6 CNC machined
Short Buffer / Sling Mount Endplate: 6061 T6 CNC machined
Trigger / Safety Selector / Mag Latch / Rail & Front Adaptor: Metal Polymer
Stock Recoil Pad & Cheek Pad: TPU
Optional Front Handguard: Steel stamping
AR-15 Lower Receiver: Mil-Spec only
AR-15 Upper Receivers:

Bufferless complete upper, e.g., BRN-180 / FM-15 / JAKL
Mil-Spec Upper + short buffer BCG, e.g., DFA MCS 2.5” BUFFER / LAW TACTICAL ARIC / CMMG 5.56 to .22 conversion BCG

What other aesthetic options or finishes are available?

Black, Tan, with or without handguard

What others are saying?:

Nothing notable as of publishing

Link to other reviews:

Recoil Web

Price point:

MSRP = $429.99

Retail = same

I need it now! Availability:

SRU Precision

Our Rating:

Pros:

Uses mil-spec AR lower receivers
Uses any AR15 trigger
Trigger system is top notch
Compact
Decent design

Cons:

Assembly can be tedious
Needs tall optics mount
Long length of pull
Extra safety selector at rear of rifle

Score: 7.50 Good

Favorite Link: Foxtrot Mike FM-15 review

Chad Wallace

March 29, 2025

Guns, review

Global Ordnance Monolith

Chad Wallace

March 29, 2025

Guns, review

Global Ordnance

Monolith Review

A little over a year ago, Global Ordnance teased their Monolith rifle and pistol. As is usual when introducing a new rifle, it took some time to get them into production. But alas, here we are. I was one of the first few to receive one to fully try out and review! The Monolith rifle has a ton of features over your standard AR15. I think you will like hearing about them.

To start with, the Global Ordnance Monolith is not your fathers AR15. Yes, most of the parts are semi-interchangeable with a standard AR15. Some of those compatible parts are the complete upper receiver assembly, trigger, and the safety selectors. For clarification, the Monolith upper can be used on a standard AR, but a standard AR upper can not be used on the Monolith. Other parts are proprietary, but in a good way.

You might ask what is in the name “Monolith”? That is where some of the improvements come in. The Monolith is designed with a single piece barrel assembly. So the muzzle brake, gas block, barrel, and barrel extension are all one machined piece. Unlike an AR15 where those would be four separate pieces. The Monolith also utilizes a 45 degree gas tube that uses a fuel injection style fitting. This eliminates needing a roll pin to hold the gas tube in place. So by re-engineering these parts, Global Ordnance has made a stronger and lighter barrel assembly that has less attached components, thus making a barrel system that has less failure points.

The first version of the Monolith comes with a Keymo style muzzle brake. As mentioned, this muzzle brake is machined into the barrel, so it is not removable. The Keymo muzzle brake was selected because it is a common muzzle device that can be used with a bunch of different suppressors. It also works very well as a muzzle brake, if you are not wanting to mount a suppressor, or live in a state that does not allow them. Threaded barrel options may be available in the future so that you can install your own muzzle brake of choice.

On the rear of the one piece barrel is the barrel extension. The barrel extension is what the bolt locks into to keep the cartridge in the chamber while firing. It also has cut outs, or feed ramps, machined into it. These help guide the cartridges out of the magazine and into the chamber. The Monolith uses an AR10 size extension. This is larger than an AR15 style, so you get more strength. The barrel is made from 4150 ordnance grade steel (the stuff they use on machine gun barrels) for added strength and barrel life. Therefore the extension is also 4150 since it is machined with the barrel. The barrel assembly/barrel extension is then thermal fit into the upper receiver. This is also done for strength, but also gives better accuracy than the slip fit of most AR15 barrels.

Instead of the standard AR style recoil buffer system, the Monolith uses a bufferless system. The recoil system, as well as the bolt, are housed inside the upper receiver. This allows various things, but the main purpose is to get rid of the AR15's buffer tube.

By getting rid of the buffer tube, one can install a true folding stock. Global Ordnance went one step farther and built the folding stock mechanism into the firearms lower receiver. The stock folds to the left side of the rifle. This gives you a rifle that can fire with the stock folded, all day long. The stock is a F5 ACR style modular stock system. The Monolith's stock is adjustable for length using some side buttons. It also has a little cheek piece that can be popped up higher. This is nice if using magnified optics. Inside the stock is also a little storage compartment for batteries or whatever. You can only access the compartment when the stock is folded. So if the stock is in the shooting position, those batteries are not falling out.

The manual of arms on the Monolith is a little different from a standard AR15. The Monolith's charging handle is a folding lever, forward of the receiver. Not the rear style like in that standard AR I keep mentioning. So the charging handle sits in the rifle's handguard, toward the top picatinny rail, on the left side. It folds forward when not in use. Otherwise, the handguard is a pretty standard MLOK style with a top rail. The charging handle can also be swapped over to the right side. The forward style charging handle works very well and is not hard to get used to.

One of my favorite features of the Monolith is that it is full ambidextrous. I already mentioned how the charging handle can be reversed, but there is way more. To start with, the lower receiver has full ambi controls. This includes the mag release, bolt release, and the safety. The safety comes with a short and long paddle, they are reversible to either side. If you want to take the grip off, you can change the safety from 90 degrees to 45. Both sides of the magazine release use a square button. The bolt releases are extended on the bottom to make it far easier to lock the bolt back. A key feature to the Monolith is the ability to drop the open bolt by just pushing down on the dust cover.

There are only a few other things about that Monolith that need to be shared. First up is the trigger. It is a flat mil-spec trigger. It is slightly better than a standard mil-spec trigger. Its pull weight is about 5.5 pounds on this rifle and feels like it has a little less creep. Global Ordnance also spec’d out a B5 grip. The grip has good texture and matches the rifle nicely. Lastly, the Monolith only weighs 5.82 pounds out of the box! With a Primary Arms 1-10x28 and a full magazine, it only weighs 7.8 pounds. So the whole package is pretty light.

The Monolith is a great rifle, but it does have some quirks. It comes with an extra recoil spring assembly. The extra is supposed to be for suppressor use. However, when I ran the Monolith with a suppressor and the “suppressor” spring, I had 2 short strokes and a failure to lock the bolt back on an empty magazine. This was in about 3 magazines. I switched back to the normal spring and it worked great, even with the suppressor. I ran around 200 rounds suppressed, after switching the recoil spring back to the original one. Other than those failures, the Monolith ran like a champ. Another problem I ran into was that I could not pull the charging handle back far enough to charge the rifle. After inspection, the charging handle carriage was binding where it goes through the receiver. I smoothed it out with a round file and have not had any problems since. The manufacturer has now since put a chamfer on the part, eliminating that problem. Lastly, the stock can flex a little if you really pull the rifle back into your shoulder. I never noticed it while shooting the Monolith, only when I was dry firing it.

Now to the good stuff. I really like how the Monolith shoots. The lightweight really makes it a joy to use. You can move from target to target quickly or get reasonable accuracy out of it. It averaged from 1.4 inches to 2 inches at 100 yards with almost any ammunition, from 55 grain up to the 75 grain. Global Ordnance supplied some 69 grain match ammo for the review, it grouped about 1.6 inches. I also really appreciated being able to drop the bolt by just pushing the dust cover down. The folding charging handle also works well as a kick stand so your hot suppressor does not touch the table and melt stuff. I also appreciated the folding stock, it is nice to have folding abilities in a rifle. Probably my favorite aspect of the Monolith is the one piece barrel assembly. Not only does it eliminate parts from the rifle, it is just a cool piece of engineering.

To improve the Monolith, I did add a few parts. Because I did not care for the trigger, I installed a flat Geissele SSP trigger courtesy of Primary Arms. This made a drastic improvement in how it feels and shoots. I am just not a fan of mil-spec triggers. During the testing, I also had a Holosun red dot mounted on it at first. Mainly it ran the Primary Arms SLx 1-10x28 with their Nova fiber dot reticle. This was a great choice for the Monolith. It let me do accuracy testing at 100 yards and do fast work up close. The Monolith was fine by itself, I just like better triggers. Plus, you can’t really do much without some sort of sight.

If you are looking for an AR that is not an AR, but better, the Global Ordnance Monolith might be it. This rifle has all the features anyone could want. Plus the monolithic barrel assembly is just a great improvement. I enjoy the lightweight and ambi features of the Monolith too. Definitely go take a look at the Monolith, especially if you are looking for something different than your standard AR15.

Firearms Insider Reviews - Key Points

Claim to Fame:

Advanced AR15 style rifle

Target Market:

Anyone wanting an ARish rifle with the features mentioned in the review

Features, Benefits, and Specifications of this product:

Caliber: 5.56x45mm
Bufferless recoil system
Monolithic 1 piece barrel
Barrel Length: 16.1"
Barrel Material: 41v50 Black Nitride
Barrel Twist: 1:7
Gas Length: Mid Length with 45 degree port
Muzzle Device: Integrated Dead Air KeyMo 2-Port Brake
Heavy Duty AR10 size bolt
Safety: Ambidextrous Manual Safety
Weight: 5lb 14oz
Overall Length: 24.5" - 31.25"
Charging Handle: Forward Side Folding - swappable from left to right
Grip: B5 Systems P-Grip
Trigger: Flat AR-15 Trigger
Stock: F5 Modular Adjustable Folding Stock
Bolt Release : Ambidextrous with EP Cover Drop
Magazine Release : Ambidextrous

What other aesthetic options or finishes are available?

What others are saying?:

5 stars at GlobalOrdnance.com

I like that you did away with the two things I dislike about the ar 15. The buffer tube and the charging handle. I like the side charging handle and no buffer tube.

Link to other reviews:

American Rifleman

RecoilWeb

Price point:

MSRP = $1234.99

Retail = Same

I need it now! Availability:

Global Ordnance, Primary Arms, or your local gun store

Our Rating:

Pros:

One piece barrel assembly
308 size bolt for added strength
No buffer tube
Lightweight
Ambi controls
Built in folding stock

Cons:

Harder to charge compared to standard AR
Charging handle locked up (current models have been fixed)
Stock flexes a little bit

Score: 8.00 Great

Favorite Link: Primary Arms SLx 1-10x28 ACSS NOVA Review

Chad Wallace

March 12, 2023

Review

Kaiser X-7 Blackbird receiver set

Chad Wallace

March 12, 2023

Review

When you think about lightweight AR’s, you usually don’t think of composite hybrids. Kaiser US is here to change that, and in a big way. Kaiser has plenty of experience in the hybrid AR market with great product success. Recently they introduced a new Titanium-Graphite composite AR15 receiver set called the X-7 Blackbird. The name pays tribute to the SR-71 Blackbird spy plane, a composite plane that was way ahead of it’s time, thus similar to the X-7 Blackbird receiver set. After having Mike, from Kaiser, on the podcast, he offered to send me one of these hot new Blackbird receiver sets for review.

Let’s talk a little about this Ti-Graphite composite. There are a lot of misnomers about composite, or plastic, receivers. Even though some of these are true, they do not apply to the Kaiser X-7 Blackbird, or any of Kaiser’s other receivers. This is because Kaiser engineered the composite receiver, so it is not just your everyday “polymer” like the others. It has more material in certain places to help with strength. But Kaiser doesn’t stop there. They wanted it to be stronger than the standard aluminum AR15 receivers. So they put titanium and anodized aluminum inserts into the places needing strength. For instance, some of these places are the threads for the buffer tube and the barrel nut threads. The Blackbird’s Ti-Graphite composite also adds in some more strength, simply because the titanium and graphite are molded into the composite. Another huge advantage to the Ti-Graphite composite is its lubricity and wear resistance. Essentially, it is so smooth that very little to no lubrication is needed. I still put some oil on the BCG, but it cycled smoothly without it. So what does this Ti-Graphite composite get you? It yields a super strong upper/lower receiver set that weighs in at 9 ounces stripped. For comparison, a standard stripped, forged AR15 lower receiver, without an upper, weighs 8.8 ounces.

Besides the Blackbird being a super lightweight receiver set, it also has some other enhancements. Up first is its textured magwell. Not only is it textured on the side, but the front as well. This texture consists of raised rectangles. For those of us that grab the magwell with your support hand, this gives you a good, no slip, grip on the Blackbird. The magwell is also beveled to help get those magazines changed quickly. Next is the fit between the upper and lower receiver. It’s tight! I have never had a matched receiver set fit like this before, in a good way. I can push the receiver pins out, hold the upper, and shake it vigorously before the two halves come apart. If you are using the Blackbird for a precision style rifle build, this fitment would be perfect and would definitely help in the accuracy department.

With the X-7 Blackbird being engineered differently, it has a few slight differences. All of them are good, just different. First, since the lower receiver is slightly wider than a standard aluminum one, at least in some spots, it can’t use standard anti-walk pins to hold the trigger in place. Standard trigger pins will work, but there is no reason to use them. Kaiser gives you their proprietary V2 anti-walk trigger pins, as well as the allen wrenches to install them. These V2 pins work for any trigger you wish to install into the Blackbird lower. It pretty much accepts any mil-spec or drop in AR trigger. The X-7 Blackbird also uses a proprietary port door on the upper receiver. As with the trigger pins, the lightweight port door assembly is also included. Most standard and ambi safeties will work with the Blackbird. I installed a Timber Creek ambi safety and it works well. Because the Blackbird is about weight, Kaiser also includes a skeletonized titanium grip screw for mounting your favorite grip. I went with the old A2 style grip, because it is one of the lighter weight grips around. The Blackbird upper receiver also does not have a forward assist. My guess is to save weight, since the forward assist isn’t always needed. The last two differences have to do with assembling the lower and upper. Instead of being able to put the rear takedown pin spring in normal, it now goes under the pistol grip, similar to the safety detent. I have zero problems with this, it's just different enough to mention. When installing a barrel and handguard onto the Blackbird, Kaiser recommends the use of a “reaction rod”. This prevents the upper receiver from being over torqued and damaged. They also only recommend 30 ft lbs of torque on the barrel nut as to not cause any unseen damage to the receiver.

A little bit about the build with the X-7 Blackbird receiver set, is in order. I wanted to try and make this build pretty light, since the Blackbird is so light to begin with. I basically took an assembled AR pistol and took it apart, that way I could use the lightweight parts on the Blackbird. These consisted of a Faxon Lightweight 10.5” pencil barrel, a Walker Defense Titanium BCG, a Dark Hour Defense Magnesium handguard, and some other miscellaneous parts. What this gave me was an AR pistol that weighed 4.2 lbs without an optic. That is with parts that one can buy everyday, no custom special parts here. If you were to put a small lightweight red dot on it, it wouldn’t weigh much more. I did install a larger red dot, a finger stop, and a light. This only brought the weight up to 5.2 pounds, which is respectable with a light. It is possible to get the Blackbird to below 4 lbs without sights, I just haven’t tried to do it yet. One could put a shorter handguard and some titanium small parts to help reduce the weight even more. I am happy with how this build turned out. When you pick it up next to my decked out 11.5” SBR, it feels like it weighs nothing.

How does it shoot? “Fantastic” would be the first word to come out of my mouth. The Ti-Graphite composite makes it so smooth. There really is barely any recoil, partly due to the Ti BCG and adjustable gas block. But It’s smoother feeling than when the same parts were in a standard aluminum receiver set. Double taps are super easy and quick to make. Essentially, this lightweight Blackbird receiver set makes an awesome place to start your lightweight AR build. I’m sure full Blackbird rifles will be available soon if building isn’t your thing.

In the end, if you are looking at a lightweight AR15 receiver set, the Kaiser Blackbird can help you out. This Ti-Graphite matched upper/lower receiver set is one of the strongest and lightest ones around. The Blackbird is way lighter than its nearest, more expensive competitor. Don’t be scared by those who say “plastic” will break, they haven’t used the Blackbird and they probably haven’t ever heard of Kaiser US either. So, if you want one of the lightest AR’s around, start with the Kaiser X-7 Blackbird receiver set and don’t look back. You’ll be getting a quality product that will perform above your expectations.