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Vltor VIS-KM Polylithic Upper with KeyMod

10/15/14 - After teasing the shooting public for more than two years, the Vltor Weapon Systems VIS-KM (Versatile Interface Structure, KeyMod) has finally been released. The VIS-KM is the KeyMod version of their VIS polylithic upper receiver.

Background - Ever since Vltor made the KeyMod system Data Package available to the public, royalty-free, back in July of 2012; the KeyMod system has been gaining momentum as more and more manufacturers have jumped on board with both KM platforms and accessories. The KM System was developed by Eric Kincel, formerly of Vltor Weapon Systems and was first introduced as a collaboration with Noveske Rifleworks. The KM System offers a mounting platform for a variety of accessories and components. Eric left Vltor to join Bravo Company USA in January of 2013 as their director of R&D.

Back in July 2012, VIS-KM prototypes already existed. The photos below are of the VIS-KM7 lower handguard without heat shield installed and the 10 and 12-inch VIS-KM uppers.

A rifle-length variant dubbed the KMA5 was also developed for the United States Marine Corp for evaluation as part of the M16A4 PIP, and was displayed at the 2013 SHOT Show. The KMA5 took the standard M16A4 barrel cluster, including standard barrel nut and handguard retainer at the front.


VIS Refresher - Before I get into the VIS-KM, here's a quick refresher on the VIS. Vltor Weapons Systems debuted their VIS (Versatile Interface Structure) upper receiver/rail system at the 2006 SHOT Show. It's a one-piece upper receiver/rail system, initially manufactured in two separate pieces, then joined together to form a single, aggregate part. The VIS upper receiver portion is patterned similar to their MUR receiver (but is a different forging). The VIS was designed to take any standard M4/AR-15 barrel. The only thing that needs to be changed is the barrel nut, which requires removal of the front sight base (a normally simple matter - even easier with non-standard FSBs). The VIS comes with a proprietary barrel nut wrench. It's not meant to be a quick-change barrel system, but it's possible to switch barrel assemblies relatively easily, if both have the barrel nuts already installed. No removal of the standard gas tube is needed.

The VIS kits come with a proprietary barrel nut wrench, to torque the proprietary barrel nut. There's no indexing of the barrel nut needed, and proper torque can be achieved. The VIS barrel nut also allows the barrel to be installed with gas tube and block already in place. The VIS upper handguard consists of the top rail and two sides, all MIL-STD 1913 compliant. Max width is about 2.2". It's heavily ventilated. Pins in the forward and mid section hold the removable lower handguard in place. The lower handguard is removable by flipping two levers, which disengage the mid pins in the upper handguard. The front of the lower handguard has cutouts which engage the front pins.

The VIS is offered in 7" (carbine), 9" (midlength), 10" (extended midlength) and 12" (rifle) versions. The VIS-KM is offered in 7", 9", 10", 12" and 14" versions.

The VIS-KM10 - Shown here is the VIS-KM10 (10" version), which is equivalent to the VIS-2A (extended midlength). The 10" version will cover a mid-length low profile gas block, whereas the 9" will end right behind the mid-length gas block. As mentioned in previous articles, the idea behind the KeyMod system is to get rid of the need for a secondary interface (rail) for attaching accessories. This allows KeyMod handguards to be lighter and narrower than a 'quad' 1913 handguard while offering a standardized interface for the ever increasing availability of KeyMod-compatible accessories and mounts. The addition of removable 1913 rail sections enables the use of legacy Picatinny-compatible accessories without the added weight and bulk of full-length rail sections as part of the handguard. The VIS-KM10 weighs about 5.5 oz less than the VIS-2A.

The VIS-KM combines a 6013T6 forged upper receiver with a 6013T6 extruded upper/lower handguard. The full length 1913 rail on the top has been retained, but the other three 1913 rails are gone. The lower handguard is removable. The KM handguard has an octagonal outside profile with seven flats to which KeyMod-compatible accessories can be mounted. For the VIS-KM10 shown here, there are 10 keyholes on the sides (3 and 9 o'clock), 12 on the bottom, and 12 keyholes at the 1:30, 4:30, 7:30 and 10:30 flats.

The 13" handguard actually measures 13.4" long on the sides. The top and bottom taper back to about 13.15". Width is approximately 1.52" and height from top of the rail to the bottom is about 1.975". Inside diamater is about 1.34".

Main features of the VIS-KM are:

  • Aircraft-grade aluminum construction
  • Hardened to T6 specifications
  • Hard coat anodized black per MIL-A-8625 Type III Class 2
  • 6013T6 forged upper and 6013T6 extruded handguard
  • Removable lower handguard
  • M203 barrel mounting compatible (with certain lengths only)
  • Compatible with most mil-spec AR-15 parts and KeyMod mounted accessories
  • VIS-KM available in forward assist version only. The VIS is available with and without forward assist.
  • Weight 20.6 oz (KM10). Weights for other VIS-KM lengths are on the Vltor website.
  • Overall length 17.596".
  • Approx Handguard width (outside) 1.74". Height (top rail to bottom) 2.24". Interior width 1.04" to 1.09" (heat shield - tapers from bottom up). Interior width (in front of heat shield 1.41")

Receiver/upper handguard - The VIS-KM utilizes the forged MUR upper receiver and permanently attaches the extruded upper handguard to essentially form a one-piece upper. The uninterrupted top rail eliminates the possibility of a separate rail system loosening up and rotating, and of a tilted or mis-aligned top rail. This ensures that any rail-mounted front and rear sights are aligned to start with.

The VIS-KM comes with the same proprietary barrel nut and barrel nut wrench that the VIS kits come with. There's no indexing of the barrel nut needed, and proper torque can be achieved easily. The open bottom of the VIS handguard, and the non-indexing barrel nut allow the barrel to be installed with gas tube and block already in place. Also included is the M203 index bracket. Installing it is not necessary unless you have an M203, but it does provide a more finished look to the bottom.



Barrel nut and wrench

Barrel nut and wrench

M203 index bracket

Lower handguard - The lower handguard is removed by flipping two rotating levers using a bullet tip or flat head screwdriver, which disengage from the pins on the inside of the upper handguard. They're a bit stiff ( a good thing) and have a detent that keeps them in the locked position that you have to overcome. The front of the lower handguard has hook tabs which engage the front pins. The lower handguard is made of 6061 T6 aluminum and is lined with a non-removable heat shield. The heat shield is attached by rivets at both ends, but it's possible to drill them out and remove the heat shield if desired (or, just use snips on the tabs). The only reason I can think of that warrants that is to allow a small-diameter suppressor to fit within the VIS-KM. The heat shield has a bead-blasted finish, and is black on the outside. One thing I did notice is that the fit of the lower handguard to the upper handguard isn't as precise as seen on Vltor's CAS-V handguards (see photo below). It doesn't affect the function, though.

Removable lower handguard


Front handguard mounting point

Lower handguard latch

Lower handguard fit

Swap - I decided to perform a barrel swap, rather than a brand new build, using an existing VIS-2A 10" upper receiver. The VIS-2A upper had served me well - this was my 'night shooting' upper for use with NODs. Also, I could just remove the barrel from the VIS without having to remove the sight tower, gas block or gas tube, and just re-use the VIS barrel nut on the VIS-KM. After I removed the barrel, I took the photos below for a direct visual comparison between the Gen I VIS and the VIS-KM. The main difference between the Gen I and II VIS is that the Gen I had machined billet upper receivers and the Gen II has the forged ones. The VIS-2A shown below also has the older forward assist block. You can see that the VIS-KM isn't just a VIS with rails machined off; it's quite a different handguard design.

VIS swap



The lower handguards of the VIS and VIS-KM are very different, as shown below, and are not interchangeable. While the heat shield on the VIS is shiny on both sides, the heat shield on the VIS-KM has a blasted finish and is black on the outside. Another difference is in the M203 Index bracket. The VIS-KM uses much smaller screws to attach it to the handguard. The torque setting should be 5-8 in-lbs, not the 35 in-lbs used on the VIS. Note that some assembly instructions included with the VIS-KM went out with the wrong information.

The upper receivers are different around the cam pin bump and transition to handguard, as are the markings on top.

Bottom details

VIS-KM and VIS lower handguards

Receiver differences


Assembly - For this upper, I used my existing barrel taken right out of the VIS 2A, and used the same barrel nut. This barrel is set up as a 'dissipator', with a low profile gas block/carbine gas system, and a Vltor sight tower clamped further forward just for the back up front sight. Yes, it's slightly heavier than using a rail-mounted front sight, but this way it takes up no rail space, which leaves room for whatever I want to mount at the front of the top rail. Installation was quick and easy - I used a receiver block to hold the upper in a vise. I stuck some card in between the barrel nut wrench and the sides of the handguard to protect the handguard should my wrench slip off the nut. It didn't, and I torqued the nut to the recommended 40 ft-lbs.

Barrel with Vltor sight tower

Barrel installation

Assembled upper

Vltor is coming out with their own line of KeyMod accessories, but in the mean time I installed some BCM KeyMod items, such as their rail sections and KeyMod Short vertical grip.

BCM KeyMod rail sections

BCM Vertical grip

The VIS-KM12 - Next up is the VIS-KM12 (12" version), or "rifle-length" handguard. With a rifle-length gas system, it'll end just behind the gas block. It'll cover up all other low profile gas system lengths. I actually had a barrel set aside for the past two years specifically for the VIS-KM12 which I had sent out to Nefarious Arm for dimpling (did a great job, by the way). Installation was exactly the same as on the KM10, and went without a hitch. With the longer 12" handguard, I get more rail space up front, but it precludes the use of a 'dissipator setup', hence the rail-mounted front back-up sight. The individual needs to evaluate what his needs/wants are when choosing handguard lengths.

Main features of the VIS-KM12 are the same as for the KM10, except:

  • Weight 22.4 oz (KM12). For comparison, the 12" VIS-3 railed handguard weighs 29 oz.
  • Overall length 19.871".


Barrel dimpled by Nefarious Arms

Barrel installed


Notes/Observations - A couple of things I noticed on the VIS-KM12 were tight lower handguard latches and larger gaps between the upper and lower handguard. The lower handguard latches on the KM12 were incredibly tight; unlocking them with a bullet tip was impossible and I had to use a screwdriver to lever them open. There's a protrusion on the side of the latch that serves as a detent, and keeps the latch locked in the closed position. I added some oil in that area and bent the latch outward slightly so it wouldn't be so difficult to dis-engage from the detent, so that helped a lot. I prefer the original VIS latch design as it's easier to open and close with and without a tool. I also noticed that the fit between the KM12 lower handguard had a larger gap than on the KM10. I'm not sure whether it's there by design, but I was using Vltor's CAS-V handguards as a comparison, with their close-to-perfect fit between upper and lower handguards.

On the KM10, which does have a small gap, the gap doesn't affect function as the lower handguard is shorter. But on the KM12, the gap, along with the increased length, contributes to lower handguard flex from side to side. It's more noticeable when using a vertical grip or bipod. I've illustrated the amount that the gap opens and closes below, with blue masking tape as a reference, using the vertical grip to flex the lower handguard from left to right. The KM12 has the same latch mechanism as on the KM10 and all the other KM lengths. On the rifle-length prototype shown above, you can see that it has two sets of latches (four in total). Since the lower handguard is attached at the front and rear, and does not engage at any other place, the longer length lower handguards are subject to flexing unless supported between the attach points. Having a gap between the upper and lower handguard allows more movement between the two, and I immediately noticed it on the KM12, but not the KM10. The solution is probably to add the 2nd set of latches into KM12 and KM14 lengths, or maybe tighten up the fit between the upper and lower handguards to minimize movement between the two. The lower handguard on the original VIS does not exhibit any noticeable movement because it is sandwiched/supported by the upper handguard along its entire length. I spoke to Vltor about it (at the time of this writing) and they replied that they had not had any other customers come bring it up as an issue (which is often the case), but are looking into solutions.

Tight latch

Lower handguard fit on KM10 compared to CAS-V

Gaps on KM12

Gap closing and opening due to flex

The approximately 5.5 oz weight savings that the KM10 has over the VIS-2A is immediately noticeable when holding both in the hand. I do not have a VIS-3 to compare to the KM12, but I'd gather that the experience would be similar. Adding back rail sections to the KM handguards will close that weight gap some, but it's unlikely that anyone will ever need full length rails on both sides and bottom. With the ever increasing availability of KeyMod-compatible accessories, the need for bolt-on 1913 rails for KM handguards will subsequently decrease.

The VIS-KM isn't as slim as the BCM KMR or Noveske NSR, which are both really skinny handguards. The KM is about .2" wider and about .25" taller overall to accommodate the removable lower handguard and heat shield. The advantage that the VIS-KM has over a separate handguard/receiver setup is the polylithic construction which ends up as a single solid entity offering the features of a monolithic upper. The handguard will never loosen up or get mis-aligned to the upper receiver rail, and there's no gap to be concerned about when mounting optics. The continuous top rail ensures that rear sight, optic and front mounted sight are mechanically aligned and centered to begin with, before zeroing. Flex between the upper handguard and receiver is essentially zero, and there is no stress on the barrel nut from barrel nut-mounted handguards.

The removable lower handguard also provides easy access to the barrel for swapping it out, or maintenance (cleaning the outside, oiling) and checking the torque of the barrel nut or set screw/clamp gas blocks. There's always the ability to barrel-mount an M203 on an M4 barrel, which was in the design intent of the original VIS.

KM12 and BCM KMR (top)



At the range, I wasn't expecting to find anything different between the VIS and VIS-KM in terms of accuracy and reliability, because those should be unaffected for what I use them for (closer range drills). I was focusing more on feel (comfort) and heat. As expected, the VIS-KM feels more lively than the equivalent VIS due to the decreased weight, and is also more comfortable for smaller handed folks like me, as it's narrower than the VIS (especially when I used rail covers on the VIS).

I had both the KM10 and KM12 uppers at the range, as well as a VIS-2, and ran 3 mags through each quickly to compare the amount of heat generated. I was surprised to find quite a large difference between the original VIS and the VIS-KMs. The rails and handguard on the VIS-2 get hot around the barrel nut area; same as most other quad rails and the handguard can eventually get quite warm. However, the barrel nut area on the KMs stayed much cooler. Usually, that area is too hot to touch, but not so on the KMs. The lower handguard, only having two main points of contact doesn't conduct as much heat from the barrel nut area either. The increased distance from the barrel and heat shield also seems to make a difference as far as heat goes; there's no need to run covers on the VIS-KM.

When shooting the VIS-KM12, I did notice the lower handguard flex that I mentioned above. I was shooting with and without gloves, and when I was shooting without, I could feel the gap opening and closing on either side as the lower receiver flexed when controlling the handguard with the vertical grip. The gap is too small to pinch fingers, and doesn't really affect function, but it prevents the lower handguard from feeling 'rock solid' like that on the KM10. After a closer look at what's happening, I don't think that there's a need to add a 2nd set of latches on the VIS-KM12; but instead close the gap or incorporate some more contact points between the upper and lower to reduce or eliminate movement.

So, after more than two years of anticipation on my part, waiting for the Vltor VIS-KM to finally hit the market; I'd say that the VIS-KM met expectations for the most part (my expectation are always set high for Vltor). I'd seen the prototypes at the SHOT show, so I had a good idea of what to expect. I do prefer the original VIS lower handguard latch design to the new one, as the new one is harder to open (for me). The fit of the lower handguard to the upper can be improved - not an issue on the KM10 but causes lower handguard flex on the KM12. I'd really love to see the KM lower handguard fit as well as the upper/lower on the Vltor CASV.

The KM handguards stay much cooler than quad rails, and I like the slimness of the KeyMod-compatible handguards. The VIS-KM isn't the slimmest handguard you can get, but it does offer features that the other ones don't (like the removable lower handguard and continuous top rail). Some folks with larger hands who find the skinny handguards too narrow may like the KM better. Overall, I'm pretty happy with the way the VIS-KM turned out.


Battle Arms Development Rifle Build

11/9/15 - Earlier this year at the 2015 SHOT Show, Battle Arms Development, Inc. (B.A.D. Inc) displayed some interesting new products in their booth, including billet receiver sets and minimalist stocks. Featured here is a rifle build using some of their new products.

Company Background - Battle Arms Development, Inc. (B.A.D. Inc.) is a design, research, and development firm incorporated in 2009 with a focus on small arms design including firearm components, tools, gauges, accessories, and complete weapon systems. B.A.D. Inc. officially launched on Independence Day, July 4th, 2009. An American and minority owned small business, all B.A.D. Inc. products are 100% made in the U.S.A. and held to the highest manufacturing standards to exceed the expectations of the most demanding end users.

I started featuring B.A.D.'s products on this site soon after they launched, like the BAD-T1, T3 and T4 armorer's tool for the M1/M1A/M14. Seeing the quality and attention to detail that they put into their products, I immediately recognized B.A.D. as a good company to collaborate with, or share ideas with. Being a lefty AR-15 shooter, I urged B.A.D. to develop their now famous BAD-ASS (Battle Arms Development Ambidextrous Safety Selector) and put in my .02 during the development of that product line. Their Enhanced Takedown and Pivot Pin sets followed, which were good examples of how even the simplest components on an AR-15 could be improved on.

This year, at SHOT, B.A.D. expanded their focus from the smaller controls to include just about everything else; featuring receivers, stocks and complete rifles. Rather than stick to the mainstream designs, B.A.D. decided to take a fresh approach to an old platform, which can sometimes be risky for a manufacturer, but is refreshing for the consumer who welcomes new and different products. While not everyone is going to like every single one of their products, the quality of their products will not disappoint.

BAD556-LW Light Weight Billet Upper/Lower Receiver Set - The BAD556-LW Light Weight Billet Upper/Lower Receiver Set started off this build. It's available as separate upper and lower, but I suspect that more people will buy the set, then purchase additional uppers for building different upper configurations. B.A.D. also offers a forged 7075-T6 Premium lower receiver with wire EDM magwell, but the lightweight set is just visually so much more interesting. The set comes packaged in nice box with precisely cut foam.

Upper Receiver - The unique-looking upper receiver is CNC machined from 7075-T6 aluminum. Aluminum upper receivers are pretty light weight already, but B.A.D. took a number of extra steps to reduce weight. Pockets of material were removed from different areas on the receiver, giving it a distinctive 'skeletonized', futuristic look. Choosing which areas to remove material from was not arbitrary; B.A.D. cut the fat; not the muscle. The BAD556-LW upper receiver has an octagon-shaped cross section that is larger than the milspec forged upper which has a round cross section. The best way to think of it is that the BAD receiver has the round cross section with reinforcement ribbing around the outside. The ribbing provides added strength and stiffness.

The forward assist has been deleted, and even the shell deflector has been hollowed out. On the top of the receiver, a channel has been cut on the flat top, and the normally sharp edges of the rail between the recoil lugs have been scalloped. The rear part above the charging handle has been beveled. All this shaves of a couple of ounces or more over the standard upper, depending on which upper you compare it to. The Light Weight upper retains the standard port cover.


  • Precision CNC from Billet 7075-T6 Aerospace Aluminum
  • Patent Pending Lightweight Design
  • M4 Feed Ramp
  • Machined T-Marks
  • Laser Engraved Logo
  • MIL-A-8625F, Type III, Class 2, Hard Anodized Flat Black Finish
  • Compatible with TDP/Mil Standard AR Upper Receiver Parts
  • All Components, material, and packaging made in the USA
  • Weight: 6.31 oz

Upper/lower set

Left side

Right side - no FA

Top and bottom

Shell deflector

Lower Receiver - The matching BAD Light Weight Lower receiver is just as unique-looking as the upper, with material removed from non-critical areas to save weigh, making it a couple of ounces lighter than most standard lowers. The lower has an integral trigger guard, with four lightening holes. The flared, beveled magazine well has cutouts on the side that reduce weight, but not function. It's also compatible with all AR magazines, unlike some billet lowers that have mag wells that extend below the mil-spec envelope. The removed material on the sides forms a sort of 'X' pattern, which is also featured at the front of the magazine well.

A tension screw (which I never use) is provided to ensure a wobble-free fit between the upper and lower, but it wasn't needed for the BAD upper - fit was solid without having to use the tension screw. I dislike tension screws because they can make disassembly of the upper and lower difficult if too much tension is put on the rear lug of the lower. If tension is needed for a looser upper, I prefer the spring-loaded type.

The bolt release catch is retained by a screw instead of a roll pin, which I've found to be very convenient, and eliminates the possibility of marring the side of the receiver during bolt catch installation or removal. Another nice touch is the captured takedown pin detent spring. It's necessary for use with the non-receiver plate version of the Sabertube butt stock. Machining and finish quality on both the upper and lower is superb.

Lower receiver left side


Bottom/top views


  • Precision CNC from Billet 7075-T6 Aerospace Aluminum
  • Patent Pending Lightweight Design
  • Laser Engraved Logo
  • MIL-A-8625F, Type III, Class 2, Hard Anodized Flat Black Finish
  • Compatible with TDP/Mil Standard AR Lower Receiver Parts
  • Dimensional Accuracy Inspection
  • All Sharp Edges De-Burred Sharp by Hand
  • Pictograph Selector Markings Properly Marked for 90° Safety or BAD-ASS-ST / BAD-CASS-ST Short Throw Ambidextrous Safety Selectors
  • Receiver Safety Selector Hole Machined with Relief Cut for Battle Arms Development "SHORT THROW" Ambidextrous Safety Selectors
  • Multi Caliber Marking for Build Versatility
  • Flared, Deep Beveled Magwell
  • Easy in Install Set Screw Bolt Catch Pin (Pin Included)
  • Captured Takedown Pin Detent Spring (Set Screw Included)
  • Integrated Trigger Guard
  • All Components, material, and packaging made in the USA
  • Weight: 6.84 oz

The bolt release catch is retained by a screw instead of a roll pin, which I've found to be very convenient, and eliminates the possibility of marring the side of the receiver during bolt catch installation or removal. Another nice touch is the captured takedown pin detent spring. It's necessary for use with the non-receiver plate version of the Sabertube butt stock. Machining and finish quality on both the upper and lower is superb.

Mag well details

Captured spring

Tension screw adjustment

Bolt catch screw

FCD Bolt catch installed

Battle Arms Development Sabertube Stock - For this build, I used the QD End Plate Model version of the Sabertube featured here previously. The Battle Arms Development Sabertube/QD End Plate/BAD-LBS Light Weight Stock combo is a minimalist stock that's made up of three components: a proprietary, unique-looking buffer tube, QD receiver end plate, and butt stock. The total weight of the combination is 6.9 oz.

The Sabertube is 1-3/4" longer than a standard carbine tube, but uses a carbine spring and buffer as the internal length is the same as a carbine tube. The Sabertube is dimpled along its entire length for weight reduction, which is its most distinctive feature. The front of the Sabertube threads into the rear of the receiver. There is no keyway for a receiver end plate, as the supplied end plate indexes using the hole in the rear of the receiver.

Sabertube and stock

Here are the features and specifications of the three components of the Light Weight Stock Combo:

(1) SABERTUBE Receiver Extension/Buffer Tube, End Plate Model (BAD-LRE-EP-M-B) for the BAD-LBS Lightweight Butt Stock.

  • Precision CNC from billet 6061 Aircraft Grade Aluminum
  • MilSpec Type III Class 2 Hard Anodized Black
  • Unique, Lightweight and Functional Dimpled Pattern Design
  • MilSpec Carbine Buffer and Buffer Spring Compatible
  • One size fits most Mid Length Buffer Tube
  • Compatible with all "Standard" AR-15 Lower Receivers (no need for captive rear takedown pin detent spring)
  • Lightweight design eliminated the need for Castle Nut

(2) QD END PLATE (BAD-QDEP-B) for the SABERTUBE Receiver Extension/Buffer Tube, End Plate Model.

  • Precision CNC from billet 7075T6 Aircraft Grade Aluminum
  • MilSpec Type III Class 2 Hard Anodized Black
  • Built-in QD Sling Attachment
  • Limited 30 deg Rotation QD

(3) LIGHTWEIGHT BUTT STOCK (BAD-LBS) for the SABERTUBE Receiver Extension/Buffer Tube.

  • Precision CNC from billet 7075T6 Aircraft Grade Aluminum
  • MilSpec Type III Class 2 Hard Anodized Black
  • Built-In Non-Rotating QD
  • Lightweight 2.8 Ounces (stock only)
  • Grade 5 Titanium Stock Screw
  • Compatible with SABERTBUE (tm) Receiver Extension Only

Stock Installation - The QD end plate version of the Sabertube has a extra distance between the shoulder and the threaded end to accommodate the added thickness of the aluminum end plate. The Sabertube threads into the end of the receiver while the end plate is placed between it and the receiver, and bottoms out on the shoulder. There are no provisions for a wrench; nor does the Sabertube lock in place. I used an improvised strap wrench to tighten the Sabertube to the receiver (which I made out of a nylon strap and large screwdriver). The butt stock is installed onto the end; clocked by eyeball and the titanium screw tightened. The Sabertube with LBS is shown below compared to a receiver with BCM stock below. The number of clicks out depends on the receiver extension. The distance from the rear of the LBS to the rear of the receiver is approximately 8.4". I used a BCM carbine spring and H buffer in the tube.

End plate on Sabertube

QD vs standard Sabertube

Length of pull comparison

Other lower components - For the other lower component parts, I used the titanium version of BAD's ETP/EPP (Enhanced Takedown Pin/Enhanced Pivot Pin) set in Black Ionbond finish. The titanium set is 50% lighter than the their standard steel set, and is CNC machined from grade 5 Titanium, then finished in black Ionbond DLC (Diamond Like Coating). The increased length and specially designed heads provide the user with more purchase and makes disassembly of the upper and lower easier.

Of course, I used the BAD-ASS ambi safety with the new scalloped lever on my support side. The magazine button is BAD's EMR (Enhanced Magazine Release) button which features a fully solid "V" shaped button face with horizontal serrations and no through hole.

The bolt catch is the new ABC/R (Augmented Bolt Catch/Release) from Forward Controls Design. The ABC/R is an augmented bolt catch/release lever that features and angled, larger top paddle and lower paddle with increased surface area. A Geissele SD3G trigger, Norgon Ambi-catch and TangoDown BG-16 Battlegrip completes the lower.

BAD pivot pin set

Pin set

BAD-ASS w/scalloped lever
Forward Controls Design ABC/R

Upper Components

B.A.D. 16" Ultramatch Lightrigid Barrel - Another new offering from B.A.D. are their barrels. Pictured here is the 16" Ultramatch Lightrigid 416R Stainless Steels .223 Wylde chamber Fluted Light Weight Barrel. It's a light weight profile (.625" gas block), fluted barrel. It weighs 24.6 oz (1 lb 8.6 oz). A standard light weight contour (pencil barrel) weighs around 1 lb 7 oz but has a thinner profile behind the front sight base. It has a non-reflective bead-blasted finish and is beautifully machined.

The Lightrigid barrel is the result of what B.A.D. feels is the best balance between weight savings and strength, rigidity and accuracy. It is a hybrid of the pencil barrel and a mid-weight profile. It's .625" diameter at the gas block for weight savings. Straight fluting is still one of the most efficient ways of maintaining strength while minimizing weight so that's what B.A.D. chose to go with. The majority of the gas pressure occurs in roughly the first couple of inches of the barrel, so it's thickened in that area so it is actually larger than a typical M4 Barrel at the chamber, but it tapers off to a much thinner diameter cross section as the gas pressure drops off significantly and not as much material/weight is needed. B.A.D. wanted to product a nice and light weight barrel that could hold relatively decent groups.

The 3D engraving of the logo on the rounded barrel is one of the most difficult part of the manufacturing process. B.A.D. chose a 1:8 twist because it can handle both light and heavy grain bullets well. B.A.D. also felt that the .223 Wylde Chamber was more accurate than a 5.56 chamber and you can shoot both 5.56 and .223 through it. The barrel is cryo treated (at the proper manufacturing step) and double heat treat/stress relieved. The finish isn't bead-blasted matte, but more of a satin finish. Not polished-reflective, but with some lustre to it. As you can see from the photos below, everything is machined and finished very nicely.

The 16" Lightrigid barrel features:

  • Gun drilled from 416R Stainless steel
  • Lightrigid proprietary barrel contour and fluting
  • 1:8 twist, 6-groove ultra precision button rifled
  • .625" gas block diameter, gas port .080"
  • Dimpled for gas block set screw
  • 1/2-28 muzzle threads
  • Mid-length gas system
  • Polished chamber and polished M4 feed ramps
  • Cryogenically treated
  • Double heat treat stress relieved
  • Not made from 3rd party barrel blanks
  • CNC machined Battle Arms Development logos
  • .223 Wylde chamber (compatible with both .223 and 5.56 NATO ammunition)
  • MPI inspected
  • Weight: 24.6 oz
  • Made in the U.S.A.

Packaging tube

Barrel markings

Muzzle end

Barrel extension

Single dimple

BAD-LGB-TI-625 Light Weight Low Profile Titanium Gas Block - .625" Dia, Raw Ti Finish - The BAD Light Weight Low Profile Titanium gas block is an ultralight 0.03 lbs (0.48 oz) with a unique 'C-shaped' side profile. The gas block is CNC machined from Grade 5 titanium, and left in a very attractive, raw titanium brushed finish. It's supplied with a gas tube roll pin and two stainless steel screws.


'C' shape

Gas tube installed

When installed to the Lightrigid barrel, the gas block sits against the shoulder; there is no handguard ring gap. The gas block slid on easily and the set screws were installed; the dimpled one first. Note that the set screws are both the same length, so the front one sticks out the bottom slightly as there's only a single dimple. I noticed that the set screws were still accessible through the KeyMod holes in the bottom of the BCM KMR handguard I installed - convenient in case a quick check of the set screws is desired.

Installed on barrel

Barrel installed to upper receiver

Set screws still accessible with KMR installed

Other - The BCM 13" KMR handguard was the logical choice for this build. Light weight, modular and slim. For an optic, I took my T-1 off another rifle and mounted it on the Fortis F1 Optics Mount - Lower Third. I decided not to mount back up folding sights for weight savings. I used the minimalist Arisaka Defense Finger Stop instead of a vertical grip; also for weight savings.

Notes/Observations - I actually started this build back in April of this year and wrote this over the next seven months as the parts started coming in. Here's the completed rifle, which I finished in June. The rifle with optic, but no magazine, weighs 5.6 lbs. This translates to a very lively feeling rifle; quick to shoulder and manipulate.

Fully assembled

At the first range visit in June, I sighted the rifle in at 50 yards with 55 gr ammunition, getting what I considered pretty darn good groups for my using a red dot sight and my lousy eyesight. Real accuracy testing of the LightRigid barrel would have to be done at a later time off a bench with a magnified optic and better ammo. Anyway, I had no problems dialing in the Aimpoint T-1, and proceeded to start shooting. I had brought along two different muzzle devices to try out from Griffin Armament; their M4 SD Hammer Comp and the M4 SD Paladin Brake. I proceeded to shoot some rounds, then quickly swap the muzzle device; then shoot some more, comparing the two. They ended up being really close in my perceived performance, but I gave the slight edge to the Paladin brake for this particular rifle.

While it's definitely unique-looking, the Sabertube stock is more comfortable than I expected (the dimples on the tube aren't sharp or abrasive), but not quite as comfortable as a regular stock with rubber butt pad. The Sabertube stock's butt pad is a bit smaller than most, so the recoil isn't distributed over quite as large an area. I liken it to shooting a HK93 with retractable stock. If I had to use the rifle for a high round count class, I'd probably switch the extension and stock out to a Vltor or BCM. The main thing you give up with the Sabertube is adjustability. Luckily, the length of pull is just about perfect for me, but may not be for taller folks.

Paladin brake and Hammer comp

Paladin installed

QD Blast shield on Paladin

I had brought along a mixture of ammunition to shoot; PMC Bronze, M193 and Wolf 55 gr Polyformance. Some folks don't shoot steel cased ammunition through their 'premium' rifles, but I'll shoot some through it to see how well it works. I've never had any issues with Wolf Polyformance ammo in any of my rifles, except that carbon seems to build up more than with other ammo. One thing I was noticing, as I started shooting, was that I was getting hit occasionally by brass in the right cheek (I'm a lefty shooter). Since I had mixed up the ammo, I couldn't tell whether it was solely the Wolf, or the other ammo as well, but it happened enough to be distracting. I got hit in both the prone and standing positions.

I was using a H buffer with standard carbine spring, and had brought along a standard buffer as well, so I swapped it out. I still got some cases in the cheek. Also, I experienced two stuck cases; both Wolf. I had to use a cleaning rod to tap them out as mortaring the rifle just caused the extractor to slip off the rim. I had never had a stuck case with Wolf Polyformance before; only with the older green lacquer cases some years back. Since the ammo worked in all my other rifles, and I had never been hit in the cheek by a case before when shooting ARs with shell deflectors, my only conclusion was that it was the smaller size of the shell deflector on the B.A.D. Light Weight upper.

Shooting righty - note empty case

When I got home, I contacted George at B.A.D. about the issue, and he had never seen it happen through all of their testing (albeit mostly right-handed). We discussed the various contributions to ejection pattern, like ammo choice etc, and it was speculated that the steel cased ammo might have been the issue, especially with the tighter chamber. While there are many factors affecting ejection pattern, the bottom line was that none of them really matter when it comes to the shell deflector - it should deflect cases away from the shooter's face no matter what angle the case is being ejected out of the port. George asked me to sent the complete upper back to him for testing.

I sent the upper back to B.A.D. with some Wolf ammo to see if they could duplicate what I was experiencing, and they couldn't, which was frustrating. It was just like taking your car into the shop with an issue which resolves itself when the mechanic checks it out. In retrospect, I should have taken video the first time, and also paid better attention to whether both the steel and brass cased ammo was hitting my cheek vs. only one or the other. I do have one photo (below) which illustrates a case being ejected past the 4:30 position. I was shooting righty just for the photo, and if I had been shooting lefty, my cheek would have been hit like the other times. George was puzzled as well, as he knows that I wouldn't just make something up, and promised to look into it further. I felt that a slight change to the shell deflector size/design would fix the issue.

B.A.D. did some further testing but we're still unable to duplicate my experience with the upper, nor had they heard of any other customers experiencing a similar issue. However, George took it upon himself to look at making some changes to the shell deflector. A few weeks later, George followed up and said that they had found another test upper ejecting at 5 o'clock, so they were going to implement the changes to the shell deflector. They also made a small change at the front of the receiver, right below the flat top rail, to make it compatible with some handguards (like the Fortis Rev II) that have anti-rotation tabs that interface with mil-spec receivers.

A comple of months later, I received the updated Gen II receiver. You can see the differences in the shell deflector below. The 'Gen II' deflector is longer and extends further forward. It's also hollow all the way through. You can also see that the lightening cutout behind it extends all the way to the back of the deflector, instead of stopping short on the Gen I. The change right below the rail is very subtle, and adds a small cutout for anti-rotation tab compatibility.

Gen I vs. Gen II shell deflectors

Top view

Side view

Front of receiver change

Rear view of deflectors

After swapping out the Gen I receiver with the Gen II one, I headed out to the range. I put about 250 rounds of mixed ammunition through the upper and did not experience a single case in the cheek, I'm happy to say. Cases ejected at about 3 o'clock consistently. The only thing that changed was the receiver - all other parts were the same, as well as the ammo used. I have to applaud Battle Arms Development's responsiveness to the issue I brought up, even though it was not a common one. At the time of this writeup, they still have not had any Gen I customers contact them with the same issue. Even so, they implemented an in-line design change to address any future concerns.

Battle Arms Development is one of the companies pushing the envelope on the AR15, and making both big and small changes to the 'platform'; both cosmetically and functionally. Some of their products might be more esoteric (like the Sabertube stock) while others are definitely mainstream (their BAD-ASS selectors for example). Either way, kudos to them for not always sticking with the tried and true formulas and daring to do things differently.

Gen II receiver

Late addition - BAD-EMMR-L Enhanced Modular Magazine Release, Large Finger Pad - The day before my second range session a small package arrived from B.A.D. Inside it was the newly-released EMMR, which features a unique, patent pending three sided dovetail finger pad attachment that allows for maximum strength, light weight and low profile.

The EMMR has a finger pad that extends rearwards to assist those with shorter fingers reach the right side magazine release button without changing their grip. The EMMR consists of a magazine button with dovetail, a finger pad that slides onto the dovetail, and a small screw to keep it there. Most add-on oversize or extended magazine buttons look a bit 'tacked on' and clumsy; the EMMR is an elegant solution that looks really good. The finger pad is skeletonized and has grooves for traction, and extends 0.5" to the rear of the button. The pads are currently available in anozided black, red or clear (silver).

A couple of notes about the finger pad design: (1) it seats flush on 3 sides to the magazine button (only extending to the rear) so it doesn't overhang and contact the fence on the lower receiver. This is especially a problem on Ambi Bolt Release lowers where the 12 o'clock position of the magazine button is very close to the bolt release latch. (2) The finger pad design angles down and away from the hammer/trigger pin areas so that it doesn't interfere or bottom out on lowers with KNS anti-rotation pins.



Button installed

Pad installed

The button itself replaces the stock button. Installation takes only a minute. I screwed the left side catch such that depressing the pad fully disengages the catch from the magazine. I'm a lefty, so I wouldn't normally take advantage of a right side button (unless I release the mag with my right thumb when changing mags), but I did shoot righty at the range to try it out. I found the EMMR to be just the right size for me to reach with my trigger finger, and an improvement over the stock button.

EMMR installed

BAD-EMMR-M Enhanced Modular Magazine Release, Medium Finger Pad - This is the EMMR with medium finger pad. It features a smaller finger pad than that of the EMMR, that doesn't extend as far back as the EMMR-L. It extends 0.35' from the rear of the button, instead of 0.5" like the EMMR-L. Other than being shorter, it shares all the same features as its longer version, and is also available in anozided black, red or clear (silver).







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