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

August 15, 2020

Review

Timber Creek Enforcer Build KIt

Chad Wallace

August 15, 2020

Review

By now, everyone knows that you can do just about anything to an AR style rifle. Timber Creek Outdoors can definitely help you with that. They have their Enforcer Build Kit. The Enforcer Kit is a complete upgrade kit for your modern sporting rifle. Besides basic black, the kit comes in a variety of colors, some anodized and some Cerakoted.

To be a little different, I asked for the Enforcer kit in purple. The purple is one of the anodized colors that Timber Creek offers. I like the look of anodizing, as it has that “high gloss” look. This purple does not disappoint. The anodizing is spot on and all the different parts match. Matching anodizing, from batch to batch, is not super easy. But Timber Creek pulled it off.

Down in the FNB section, it shows what all comes with the Enforcer kit and it is a lot. I’ll go over most of the parts individually, at least the important ones. All of the parts come in one nice box. Small parts are in bags, in the buffer tube. On the back of the box is essentially a parts break down, and where those parts go. I also put together a list of what else is needed to complete a full rifle. Some of these parts can also be purchased from Timber Creek, like the barrel and castle nut, these additional parts are as follows:

Castle nut
Buffer and recoil spring
Trigger
Bolt catch
Mag catch
Upper/lower
Buffer retaining pin & spring
Barrel
Stock
Gas tube

First up I’ll start with the lower receiver small parts. The extended mag release has a nice little downward curve to it and isn’t too large. I really liked it’s function as it isn’t any higher than the standard mag release, it just sits back closer to the trigger finger. TC’s oversize trigger guard is wider also. It’s pretty oversize, so much so that I think a Sasquatch could get his finger in there. Then there are the take down pins. They add color, but are undersized in the kit I received. They wobble around and make the upper to lower fit, fit loosely. I had standard pins in this kit before, and they didn’t have these problems. Maybe not a small part, but it attaches to the lower, is the mil-spec 6 position buffer tube. It does not, however, come with a castle nut. A QD endplate is also included.

Also included for the lower is an ambi safety selector. This safety is reversible, meaning that it is either 45° or 90°. I was happy to see this, as I like 45° safeties, so that is how it was installed. Two selectors are provided, one is about standard length, the other one is shorter. This is pretty standard for ambi-selectors. They attach to the safety selector piece with some allen head screws, I did use a little Loctite 242 when installing them. I wasn’t sure how I was going to like the shape of the safety, it is a kind of tear drop shape with serrations . After using it, I do really like it, especially the serrations. These serrations let my thumb know that it is in contact with the safety.

The Timber Creek pistol grip is one of their oldest products. As with all of the Enforcer kit parts, it is aluminum and CNC machined. They skelontonized the grip to save weight. It has a finger rest/stop at the heel to help prevent your hand from sliding off. There is also a beavertail for comfort. Plus some grooves on the front to aid with grip. In my opinion, the grip is a little on the slick side. It is very comfortable, but needs a little more texture to help me grip it.

Next we move on to the upper receiver. Only two small parts here, the dust cover and forward assist. The dust cover adds a nice contrast to the upper. The one supplied doesn’t like to stay closed. If you bump the rifle too hard, installing a magazine for instance, the door flips open. The forward assist works as expected. It has checkering on the face of it for extra grip, just in case you have to use it.

Timber Creek’s Enforcer charging handle is a work of art. It has ball bearings inside it, thus giving the handle arms super smooth actuation. The oversize handles stick out a bunch on either side, making it truly ambidextrous. By making the handles so large, one hand operation is extremely easy. Even if one were to mount a large scope, they would have easy access to the charging handle. The handles are slightly curved forward with grooves on the front face. Pretty much eliminating your hand from slipping off during use. I personally would have liked Timber Creek’s small charging handle to be in the kit, as this one is just a tiny bit too big for my liking. It is, however, an excellent charging handle.

Probably one of the most notable parts in the kit, is the 15” Ultralight Enforcer handguard. This handguard is super skeletonized and weighs nothing. If you pick it up by itself, without the barrel nut, it is like picking up air. The complete handguard assembly weighs something like 7.6 ounces with the barrel nut! Since it is the ultralight version, the handguard has a short rail at the front and back instead of running all the way across the top. I really like these style of handguards, as I never use the middle of the pic rail anyhow. There is a unique “Timber Creek” curve at the nose of the handguard. This curve is useful to keep brush and stuff from getting caught in it out in the field. Plus, it looks pretty good also. Now, if you need to attach anything else, the handguard has M-Lok slots running along the top, sides, and bottom. There are also QD holes for attaching slings and such. These are the good ones that have anti-rotation cuts every 45°. There are five total. One on each side, at the front and rear of the handguard. Then there is one on the bottom rear, just in front of the clamping system. Timber Creek uses a clamp system, with some extra set screws, to hold the handguard on. There are also wings, that extend over the upper receiver, to help keep it from rotating. I think the clamp system works just great, so the probably didn’t need the wings. But, extra insurance is always a good thing. For as light as this handguard is, there is less flex in it compared to other lightweight handguards. At least that’s my experience with the same length ones that I have used. The Enforcer lightweight handguard is well worth the price of admission.

To round out the kit, Timber Creek throws in their muzzle brake and gas block. The gas block is low profile to fit under the handguard. It is the two set screws on the bottom type and about an inch long. It looks goog, and works great. The “Heart Breaker” muzzle brake is a two chamber style, with two holes on the top to reduce muzzle climb. The chambers are heart shaped, hence the name. I was hesitant about this brake at first. Yes, the brake proved me wrong. It works way better than I had ever imagined. It is really loud, but that was expected. My daughter even mentioned the lack of recoil while using it. Instead of a crush washer or shims, the Heart Breaker comes with a locking jam nut. Think of it as a nice little bonus in the Enforcer kit.

Now that all the parts are pretty much covered, here’s my thoughts. If you value quality parts, these are top notch. Timber Creek did an awesome job with most of the stuff in the kit. I really enjoy shooting this rifle, it handles so nice with the lightweight parts. The rifle in the pictures weighs in at 6 lbs 14 ounces with the red dot. But, it uses everyday standard internals and a 16” heavy profile barrel (lightweight barrel would save roughly 8 ounces). The handguard and ambi-safety are probably my 2 favorites. They just work great.

The Timber Creek Enforcer Build Kit is a great upgrade. If you are looking to build a new rifle, add color, or just upgrading your old one, the Enforcer kit is pretty much a worthwhile option. One might think it is a little pricey, but you are getting quality parts. These parts would definitely cost you more if you were to buy them individually. Definitely go check out Timber Creek Outdoors and all of their stuff.