Update & Patreon

We put the video above together to hit our main points but please read on for more information.

Hi guys,

A few weeks ago we mentioned the TAB Patreon page for the first time at the end of a video, so we thought it was time we explain why we’ve launched it and our hopes for it. When we launched TAB just over a year ago, we set up a Patreon page for future use but we decided we would wait to launch it. As I said at the time we felt we wanted to show you what we wanted to accomplish and show you we were worth your time and money to support. But a few people spotted the links and signed up as patrons – to those early Patreon supporters – thank you!

We’re still a small channel but we recently passed a few important milestones. We now have approaching 40 videos live, an amazing 2,500 subscribers and we recently passed 100,000 total views! With that we hope we have shown that we are serious about producing detailed, thoroughly researched, well made videos and articles. We appreciate everyone that watches, likes and comments – it makes the work that goes into the project worth while. So we thought it was time to mention the Patreon page publicly.

It’s important to note that Vic and I are not in this for the money. We love history, we love firearms and we love researching and telling the story of incredible designs like the Ferguson Rifle, the HK G11, the AR-10 and the Curtis bullpup to name just a few. When we set up TAB we made the conscious choice not to monetise the channel through YouTube, which at the time had deleted and suspended several gun channels. We felt that the best thing to do was to avoid YouTube’s algorithms and stay under the radar, at least until we were established. Little seems to have changed since then, friends’ channels like Bloke on the Range and BritishMuzzleLoaders have since had strikes, demonetisations and even deletions! TAB is still ‘demonetised’ and probably will continue to be for the foreseeable future. We would prefer to be viewer supported by our community of viewers.

So if you would like to help towards the upkeep of the TAB website, help us buy equipment and research materials or help us travel to collections then we are sincerely grateful and we appreciate every dollar, pound, euro and penny that is donated to us!

What do we share on Patreon?

Over on the Patreon page we currently have two tiers of supporter, you can find out more about those here. At the moment we share behind the scenes photos and content showing you sneak peaks at upcoming videos and how they’re produced. The Patreon Lens feature (basically Patreon’s version of Instagram Stories or Snapchat) is great as it lets us share quick clips and photos easily. We’ll often post several of those a day when working on episodes, often showing you how we research, film and edit.

We also post blogs about upcoming research trips, the arrival of new research materials/books and share photos of guns sometimes weeks or months before the episode covering them is finished and ready to be posted. In the future we hope to do Q&A videos/streams and have some tangible perks (a TAB t shirt might be cool?) too. This is something we will be working on in the new year.

If you are one of the handful of people who have supported us through Patreon over the last few months, once again thank you. If you have just heard about it or have just found the page and this post then I hope you’ll consider putting in $1 a month to support our work, we have grand plans and many more interesting historic small arms stories to share – we really appreciate it, thanks for reading!

You can find out more over on the TAB Patreon page here

Thank you – Matt & Vic

Steyr AUG Para 9x19mm Submachine Gun

The Steyr AUG or Armee Universal Gewehr (Army Universal Rifle), is one of the earliest Bullpup military issued rifles (if not the earliest) adopted by a military, i.e. the Austrian Military as the Stg77 in 1977. Other early bullpups being the British L85 (SA80), and the French FAMAS. The AUG went on to be adopted by the Australian military and eventually licence built there as the Austeyr F88, the New Zealand Defense Forces, Irish Army, and various other military and police forces worldwide.

AUG PARA
Belgian Federal Police officer with AUG 9x19mm SMG (source)

In 1990, Steyr developed the first variant of the AUG/9mm Carbine and a 9mm conversion for the AUG-A1 rifle. The conversion consists of a new bolt group, barrel and magazine-well insert. The AUG/9mm Carbine uses the standard 25 round or 32 round magazines from the Steyr MPi 69/81 submachine gun series which is also a Steyr product. Whilst the conversion of standard rifles with the conversion kit is perfectly viable there were difficulties with the standard ejection port due to fired cases rebounding back into the action and also striking the firer!

The 9mm conversion ‘kit’ was replaced with the second variant of the ‘dedicated’ AUG Carbine in 9mm with an improved magazine-well adapter and an ejection-port shield or barrier, this could also be retrofitted on existing 5.56mm housings as an improved conversion kit including an ejection-port shield. However, in 1995 a dedicated AUG /9mm Carbine was introduced with the ejection-port shield molded as an integral part of its stock/housing (the marketing of the 9mm conversion kit being discontinued).

AUG 9mm carbine
Steyr AUG-SA 9x19mm Carbine Conversion (RIA)
Steyr AUG A3 XS
The latest iteration of the weapon the Steyr AUG A3 XS, note the lack of ejection port on the left side and the picatinny optics mounting rail (source)

The AUG/9mm Carbine the barrel does not have a flash suppressor, but has a threaded section behind the muzzle to allow the mounting of aftermarket suppressors etc. The barrel mounts exactly the same as the 5.56mm barrel but does not have a gas tappet system as the 9mm carbine functions as a closed-bolt, blowback. The bolt of the 9mm variant is integral with what is normally the bolt carrier in the standard AUG, the bolt face is machined directly in the bolt carrier face.

AUG PARA1
Belgian Federal Police officer with AUG SMG with ejection port case deflector (source)

Users of the 9mm variant are mostly police or security forces, notably the Kuwaiti Military Police fielded the 9mm SMG/carbine for some time until surplused a few years back. Ironically the 9mm SMG/carbine is fielded by the Belgian Federal Police whilst the Austrian Gendarmerie used to field the FN (Belgium) manufactured UZI!

If you enjoyed the video and this article please consider supporting our work here.


Specifications:

Calibre: 9x19mm
Action: Blowback
Overall length: 61cm (24 inches)
Barrel length: 32.5cm (12.8 inches)
Weight empty: 3kg (6.6lbs)
Magazine capacity, rounds 25 or 32 round box magazines
Cyclic rate: ~700 rpm


Bibliography:

Sub-Machine Gun: The Development of Sub-machine Guns and Their Ammunition, M. Popenker and A.G. Williams (2011)

Steyr AUG Submachine Gun Manual, Steyr(1990)

The Micro UZI

This week Vic brings us both a video and blog on the Micro UZI

The Micro UZI was an oddball in the UZI family, it was derived from the UZI Pistol which was itself born of an idea to get another IMI product introduced into the US civilian marketplace after the success of the full size UZI carbine by the then importer Action Arms. To get around, or at least comply with the strict US BATF regulations as to what a pistol constituted, a miniaturised  variation of the full size UZI was proposed. It had to have the ‘look’ of an UZI but be manageable to handle and shoot with one hand. This required more work than had been involved in the development of the Mini UZI.

The pistol had to have a closed bolt and only fire semi-auto, no buttstock could be fitted on the pistol as this would contravene BATF regulations. The bolt was based on the Mini UZI bolt and the striker but redesigned to be more compact to fit the much shorter receiver. A blocking catch similar to the then recently released model ‘B’ UZI Carbine, was fitted to the bolt. This was a safety device that prevented the gun firing ‘out of battery’. The receiver was the same height and width as all the other UZI family but considerably shorter. To reduce weight the receiver stampings were of 1.5mm material and not 2mm as per the full size & Mini UZI.

The UZI pistol was introduced onto the civilian market around 1984. It eventually was sold in the following calibres: 9mm, 9x21mm (Italian market), .41 AE, and .45 ACP.

Argentine Special Forces.
A joint service special forces team member from Argentina, with a Micro Uzi, posts security during a multinational amphibious beach assault training exercise in Ancon, Peru, July, 2010. (source)

In 1985 IMI realised that the UZI Pistol could be modified to be a compact and effective SMG. To convert it to full-auto fire the lower lip of the bolt which was milled off during manufacture of the semi-auto pistol was left in place. The selector block on the trigger assembly was removed and a folding stock, which was smaller than the Mini UZIs was fitted. The open ‘U’ notch rear sight from the pistol was replaced by a traditional ‘peep’ sight, and finally the barrel from the pistol was lengthened to 5.25″ and compensator notches milled into it to reduce muzzle flip and help control the gun whilst firing. The Micro UZI had a phenomenally high rate of fire at 1,800 rounds per minute, hence most guns were fired in semi-auto only (note that the example I filmed has the selector ‘blocked’ to prevent full-auto selection)!

It is also interesting to note that the Micro UZI was the first gun in the UZI family that started off as a semi-automatic gun and became a full-auto one!

If you enjoyed the video and this article please consider supporting our work here.


Specifications:

Overall Length: 46cm / 18 inches
Length (with stock folded): 25cm / 9.8 inches
Weight: 1.5kg/ 3.3 lbs
Action: blowback
Calibre: 9x19mm & various (see text)
Cyclic Rate: 1500-1800 rounds
Feed: 20, 25 or 32-round box magazines

 

British Trials Browning Automatic Rifle

During World War One the British Army had been early adopters of the light machine gun concept, recognising the mobility and firepower offered by the Lewis Gun as early as 1915. Despite the Lewis Gun’s proven track record after the war a lighter weapon was sought.

In the final months of World War One the US had begun fielding the Browning Automatic Rifle, Model of 1918, in what they had envisaged as a ‘walking fire’ role. Relatively soon after the war British Ordnance began the search for what they termed a ‘light gun’. They took an interest in the BAR ordering 25 Colt Model 1919 commercial guns for testing and evaluation at a cost of £1,575 in November 1920. According to James Ballou’s book on the BAR, Rock & a Hard Place, the serial numbers of these guns ran between C-100374 to C-100398. The Colt Model of 1919 differed little from the earlier US military model, the principle changes were the lack of a flash hider and the use of relocating of the recoil spring to the butt, acted on by a transfer rod, from inside the gas cylinder tube.

This batch of guns was adapted to chamber the rimmed British .303 round, necessitating a curved magazine, a .303 barrel, an adapted bolt, extractor and ejector. In April 1921 the BAR along with four other light machine guns (the Madsen, Beardmore-Farquhar, a Lewis Gun and strip and magazine fed Hotchkiss guns) at the School of Musketry at Hythe.

Colt Model 1925
Colt Model 1925 Browning Automatic Rifle (Royal Armouries)

The Browning fared well in the testing with the evaluating officer stating that for a “light gas-operated weapon the Browning has done remarkably well…” In fact the Browning was selected as first preference out of the five weapons tested. The testing board felt it was suitably light and would be the cheapest to manufacture. The board made a series of suggestions to improve the BAR for British service:

  1. Move the cocking handle to the right side of the weapon
  2. Fit a light bipod which is height adjustable 
  3. Ejection port and magazine well dust covers
  4. Gas regulator hole to be clear of threads of regulator
  5. Improved method of fixing position of gas regulator
  6. Stronger  butt
  7. Magazine well capable of receiving Lee-Enfield rifle magazines

No further action was taken until 1927 when it was decided that the Superintendent of Design should adapt several Brownings to improve the weapon for British service.  According to Jame Ballou’s book these new modified BARs were not all from the original batch of test guns, at least one was a Colt gun purchased through FN.

The adapted BARs had carrying handles, flash hiders, bipods, Lewis Gun-style pistol grips, new rear sight and protected front post, an ejection port dust cover and a redesigned butt stock. A number of other changes were also made including switching the charging handle to the right (this change was found to be less necessary with the addition of a pistol grip).

26262
Specially adapted British 1925 Trials BAR (Royal Armouries)

While the modified BAR’s came fairly close to being adopted the principle problem remained the weapon’s limited 20 round magazine. Various larger magazines such as a 40-round box magazine from Colt and a 30-round drum were considered. By 1930 several new light machine guns had appeared and the Browning was beginning to look obsolescent. The Czech vz. 26 would eventually be adopted as the Bren.

We recently had the opportunity to examine what we believe to be a British trials BAR. Vic examined the gun finding that rather than a commercial Model of 1919, purchased for the first set of evaluations, it was marked as a Model of 1925. Interestingly, however, rather than resembling a Colt M1925 it had all the characteristics of an earlier M1919.

TAB 303 BAR (2).Movie_Snapshot
A still from Vic’s video showing the disassembled .303 Model 1925 (TAB)

The gun examined, serial number C-102723, falls outside of the serial range James Ballou states belonged to the 25 original .303 BARs. While it is marked M1925 the gun shares none of the characteristics of an M1925 – lacking the reshaped wooden foregrip, stubby pistol grip and rate of fire reducer. It does, however, have the 1919’s style of stock, foregrip and its relocated recoil spring. Additionally, the gun has had a folding carry handle, very similar to that of the later British trials BARs, added.

With little solid information available there could be a number of reasons for this. Perhaps the BAR Vic was able to examine was purchased for the later trials (between 1925-30) and it underwent minimal alterations – there is some variation between the documented surviving examples. The discrepancy between parts and the model name is curious. It is possibly a mix of parts were used to assemble the weapon during experimentation with configurations and an M1925 receiver was used as the basis of the gun but it was assembled with an M1919 barrel and furniture.

If you enjoyed the video and this article please consider supporting our work here.


Specifications:

Length: ~115cm / 45 in
Weight: .303 M1919 approximately 7kg, later trials guns between approximately 7.5-8.5kg
Sights: M1917 Rifle sights
Action: Gas-operated, rising bolt lock
Calibre: .303
Feed: 20-round curved box magazine


Bibliography:

The Browning Automatic Rifle, R.R. Hodges, (2012)

Rock and a Hard Place: The Browning Automatic Rifle, J.L. Ballou, (2000)

Video from the Institute of Military Technology showing a .303 M1919 BAR (source)

Colt Advanced Combat Rifle

This is the final of three introductory videos looking at the US Army’s ACR prototypes. We will be revisiting these rifles later to show disassembly and how they worked. You can check out our introduction to the H&K G11 here, our look at the AAI ACR here, the Steyr ACR here and  you can also find our in-depth ACR Program overview article here.

Colt’s entry was perhaps the most conventional of the designs submitted. Based on the rifle the program sought to replace. Colt’s ACR was essentially an improved M16, which fired both conventional 5.56x45mm ammunition as well as a new 5.56mm duplex round. While the duplex round increase hit probability at shorter ranges, it impacted long range accuracy requiring the additional use of conventional M855 rounds.

DSC_0141
Colt ACR rifle submission Left and right side views of the Colt ACR (Matthew Moss)

It incorporated a variety of improvements including a new oil/spring hydraulic buffer to mitigate recoil. This resulted in a major decrease in the weapon’s recoil, Colt suggested as much as a 40% mitigation. A reshaped pistol grip and a hand guard which mounted a sighting rib for snap shooting – this stemmed from recommendations from the Human Engineering Lab. The weapon had a flat-top upper receiver which incorporated a weaver rail so a 3.5x optic (an early ECLAN) or a more conventional sight/carrying handle could be fitted.

DSC_0139
(Matthew Moss)

The rifle’s collapsible six position telescopic butt stock was an improved version of that offered with Colt’s carbines. When at full extension the Colt ACR was the longest rifle tested, at 40.6 inch or 103 cm long. A distinctive proprietary muzzle brake compensator (MBC) designed by Knight’s Armament was also added. The Knight’s MBC reduced the rifle’s report by 13.5-decibels and also played an important role in recoil mitigation.

DSC_0138
Close up of the Knight’s Armament designed muzzle device (Matthew Moss)
DSC_0137
Right-side close up of the rifle’s receiver and rail mounted Eclan sight (Matthew Moss)

Colt’s duplex rounds were developed by the Olin Corporation and placed two projectiles nose to tail. The projectiles were copper jacketed steel penetrators. In theory the lead projectile would strike at point of aim while the second would strike somewhere near point of aim with in a theoretically limited area of dispersion. The forward round was 35gr while the second was slightly lighter at 33gr.

Colt's 5.56mm Duplex round (US Army)
Colt’s 5.56mm Duplex round (US Army)

During testing one of the duplex rounds was not properly seated inside the cartridge case and when fired became lodged in the barrel and during the course of fire and the weapon’s barrel blew when another round was fired. This was addressed by a slightly larger propellant charge.

Another negative to the Colt entry was that, in addition to having to carry two types of 5.56mm ammunition,  its duplex round offered no improvement in weight and was infact slightly heavier than standard M855 ammunition. While the hydraulic buffer, muzzle device and furniture were not used later, some of the features developed for the ACR entry were later employed in the M16A3 and later A4. These included the selector configuration and the flat-top upper receiver.

If you enjoyed the video and this article please consider supporting our work here.


Specifications (From ACR Program Summary):

Length: 40.6 inches / 103cm (extended) and 36.7 inches / 93.2cm (collapsed)
Weight: 10.3 lbs / 4.67kg
Sights: iron or 3.5x optic
Action: Direct gas impingement
Calibre: 5.56mm duplex round & M855 ball
Feed: 30-round box magazine

You can find out overview article on the ACR program and all of the rifles here


Bibliography:

Advanced Combat Rifle, Program Summary, Vol.1, ARDEC, 1992 (source)

‘Revisiting the SPIW Pt.3’, Small Arms Review, R. Blake Stevens, (source)

The Black Rifle II, C. Bartocci, (2004)

Our thanks to the collection that holds these wonderful examples of the ACR rifles


Please do not reproduce photographs taken by Matthew Moss without permission or credit. ©The Armourer’s Bench 2018

Steyr Advanced Combat Rifle

This is the second of three introductory videos looking at the US Army’s ACR prototypes. We will be revisiting these rifles later to show disassembly and how they worked. You can check out our introduction to the H&K G11 here, our look at the AAI ACR here and  you can also find our in-depth ACR Program overview article here.

By the mid-1980s Steyr-Mannlicher were already leaders in unconventional small arms designs. In 1977 the Steyr AUG was adopted by the Austrian Army becoming the first generally adopted bullpup service rifle.  As such Steyr-Mannlicher’s entry was inevitably a bullpup. Designed by Ulrich Zedrosser the rifle used a gas piston driven rising chamber mechanism which rose and fell to chamber rounds.

DSC_0118
DSC_0115 Left and right side views of the Steyr ACR, note the small AUG-style (Matthew Moss)

The rifle’s action is described in a 1988 patent (US #4949493) granted to Zedrosser, it explains that ” chamber member, which is separate from the barrel… is reciprocable between a firing position and a loading position in a direction which is transverse to the longitudinal direction of the barrel.” This means that the chamber rises and falls, with the rifle firing from an ‘open bolt’.

The patent goes on to explain the weapon’s action:

When the chamber member is in its loading position its chamber is freely accessible and at one end communicates through a loading opening of the firing block with the interior of a magazine holder and at the other end communicates through an ejection opening of the firing block with an ejection shaft. For the performance of the loading and unloading operation, a slider is provided, which is movable in the longitudinal direction of the barrel and carries a feeder, which is movable from a first end position… when the chamber member is in its loading position, and the movement of the chamber member from its loading position to its firing position is adapted to be initiated before the feeder reaches that end position in which the feeder extends into the loading opening.
Steyr_ACR_layout_schematic
Patent drawing showing the Steyr ACR’s bullpup layout (US Patent Office)

One of the other patents (US #4817496) protecting the design explains the weapon’s gas system:

In order to provide a gas drive which is particularly simple and functionally reliable, light in weight and compact, the barrel is provided with a collar or the like, which constitutes a stationary pneumatic piston, and the pneumatic cylinder consists of a sliding sleeve, which surrounds the collar and is longitudinally displaceable between stops.

US4949493-1
Patent diagram showing the Steyr ACR’s action (US Patent Office)

The Steyr ACR, like AAI’s entry, fires flechettes but Steyr’s are housed inside a cylindrical polymer case. The bullpup Steyr was the second shortest at 30 inches (76cm) and the lightest of the rifles submitted weighing 8.5 lbs (3.86kg).

The Steyr ACR borrows its ergonomics from its conventional forebearer, the AUG. With a moulded green plastic stock and a similar pistol grip, magazine release, trigger and safety layout. Unlike the AUG, however, the ACR uses an AR-15 style charging handle located at the rear of the sight mounting block and the stock extends further forward to encompass the barrel and gas system. The rifle could be fitted with a variable 1.5x to 3.5x optic or use iron sights.

DSC_0150
Comparison of the Steyr ACR with the earlier AUG (Matthew Moss)

As discussed earlier the rifle does not use a conventional bolt, instead it uses a rising chamber, as a result the rifle fired from an open bolt. A live round only entered the chamber after the trigger had been pulled, thus reducing the potential for cook-offs. Spent polymer cases were pushed out of the chamber and ejected from an opening just in front of the magazine well.

Steyr's Polymer Cased Flechette round (US Army)
Steyr’s Polymer Cased Flechette round (US Army)

Feeding from a 24-round box magazine, made from the same translucent material used in conventional AUG magazines. The magazine goes from double stack to single stack, to allow it to feed reliably, as a result the capacity had to be shortened. A high capacity drum magazine was planned but not provided for the trials. The polymer case held a fin stabilised 9.85 gr flechette with a moulded four piece sabot which broke up soon after exiting the muzzle. This was identified as a shortcoming as it risked hitting nearby troops.

ACR Program Summary recognised the Steyr ACR entry as “the simplest weapon, the simplest round, and the most cost effective approach of any of the ACR contenders.” The report noted that the weapon’s “greatest current deficiency is its poor round to round dispersion characteristics.” This was a criticism levelled at both the flechette firing entries, it essentially ended the US Army’s interest in flechette firing individual weapons, relegating the concept to larger area effect weapon systems.

If you enjoyed the video and this article please consider supporting our work here.


Specifications (From ACR Program Summary):

Length: 30 inches / 76cm
Weight: 8.5 lbs / 3.86kg
Sights: Iron or variable 1-3.5x optic
Action: gas-operated, rising chamber
Calibre: 5.56mm plastic cased flechette
Feed: 24-round magazine

You can find out overview article on the ACR program and all of the rifles here


Bibliography:

Advanced Combat Rifle, Program Summary, Vol.1, ARDEC, 1992 (source)

‘Revisiting the SPIW Pt. 1-3’, Small Arms Review, R. Blake Stevens, (123)

Steyr’s ACR entry was extensively protected by various patents:

US #4944109
US #4817496
US #4930241
US #4949493
US #4916844
US #4760663
US #4739570
US #4941394

Our thanks to the collection that holds these wonderful examples of the ACR rifles


Please do not reproduce photographs taken by Matthew Moss without permission or credit. ©The Armourer’s Bench 2018

AAI Advanced Combat Rifle

This is the first of three introductory videos looking at the US Army’s ACR prototypes. We will be revisiting these later to show disassembly and how they worked. You can check out our introduction to the H&K G11 here. You can also find our in-depth ACR Program overview article here.

The AAI Corporation was founded in 1950, as Aircraft Armaments, Inc., and has long been involved in advanced firearms design, taking part in a number of the US military’s previous small arms programs. Throughout the Cold war AAI was involved in the US Army’s search for a new advanced infantry weapon system. Before we examine the AAI ACR, it is important to understand the context in which it evolved.

The Special Purpose Individual Weapon (SPIW) program, an off-shoot of Project SALVO began in the early 1950s and ran until the late 1960s. During the SPIW program AAI developed a series of designs, including an entire family of weapons, which used flechette technology. These culminated with the XM19 rifle, or SFR – Serial Flechette Rifle.  The XM19 represented the pinnacle of over a decade of flechette technology development, however, the end of the US war in Vietnam saw the need for SPIW disappear and the program was wound down.

4 guns from AAI's family of weapons 60s SPIWs
AAI SPIW family of weapons from the early 1960s (Reproduced in Stevens & Ezell’s SPIW Deadliest Weapon)

In the early 1970s SPIW essentially morphed into the Future Rifle Program, but with the end of US involvement in Vietnam, this also proved a failure. During the early 1980s the US Army awarded development contracts to both AAI and Heckler & Koch to develop caseless ammunition and a weapon system capable of firing it. While H&K G11 is no doubt the better known of the two weapons, AAI’s Caseless Weapon, while a move away from flechette technology, was also an interesting design.

AAI's Caseless Ammunition Rifle (US Army)
AAI’s Caseless Ammunition Rifle, another image available here (US Army)

Firing a variety of ammunition the AAI design was capable of firing a high cyclic rate 3-round burst at 1600-1800rpm. The ACR program summary report noted that the AAI Caseless project was feasible and only lacked development funding to make it a reality, as the design was much simpler than the G11.

AAI were one of six companies to respond to the ACR program’s Request for Proposals, released in September 1985. AAI’s ACR was an evolution of the earlier SFR/XM19 rifle. The weapon AAI submitted was gas-operated, fed from a 30-round box magazine, and fired a brass cased flechette round in either single shot or a high cyclic rate three round bust – fired at a cyclic rate of ~1800rpm.

Left of the AAI ACR rifle (Matthew Moss)
Left-side view of AAI Corporation’s ACR entry (Matthew Moss)
AAI Corp ACR rifle (Matthew Moss)
Right-side view of AAI’s ACR entry (Matthew Moss)

AAI’s ACR fired from a closed bolt and used a muzzle device to reduce muzzle climb during burst firing. The 1990 ACR Program Summary report explains how the rifle’s gas system worked:

“…incorporate an ‘entrapped gas’ operating system. Gun gases enter a cylinder, drive a piston to power the system, and prevent any leakage of propellant gases and residues into the other mechanism parts.”

AAI developed a polymer saboted steel 10.2 gr ‘sub-calibre’ flechette which fitted within a standard M855 brass case. As a result the rifle used a proprietary magazine to avoid the accidental chambering of conventional 5.56x45mm rounds. The flechette rounds had a muzzle velocity of 4,600 ft/s with propellant produced by the Olin Corporation.

DSC_0146
An AAI Corporation ACR marked serial number 20 (Matthew Moss)

The rifle was designed to mount a quick detachable 4x optic and also had a white-highlighted shotgun-style rib sight along the barrel to aid snap shooting. The rifle was one of the longest entries with an overall length of 40 inches or 101.6cm. Interestingly, rather than a push-button magazine release, AAI opted for a large paddle release.

Front end of AAI ACR (Matthew Moss)
The fore-end of the AAI ACR, note the front sight post and muzzle device which reduced muzzle climb during burst firing (Matthew Moss)

AAI’s rifle borrowed some of its external ergonomic characteristics from the M16A2, then in service. With a moulded polymer pistol grip and butt, forming part of the lower receiver, shaped to mimic the M16’s. It also utilised the M16’s sling loops and butt plate.

According to the ACR program summary the AAI entry proved to be a “mature design which performed in a reliable fashion” during the field trials. It was regarded as a weapon with known reliability with a flechette round superior to the Steyr, the other flechette-based entry.

AAI ACR Ejection Port (Matthew Moss)
Close up of the right-side of the AAI ACR, note the ejection port and moulded plastic case deflector, selector level, paddle magazine release and sight mount (Matthew Moss)

Today, AAI continue to develop both small arms and other defence technologies. Now a part of Textron, they are currently involved in the US Army’s Lightweight Small Arms Technologies (LSAT) program.

If you enjoyed the video and this article please consider supporting our work here.


Specifications (From 1990 ACR Program Summary):

Length: 40 inches / 101.6cm
Weight: 9.39 lbs / 4.26kg
Sights: Iron or 4x optic
Action: Gas operated
Calibre: 5.56mm brass cased flechette
Feed: 30-round box magazine

You can find out overview article on the ACR program and all of the rifle here.


Bibliography:

Advanced Combat Rifle, Program Summary, Vol.1, ARDEC, 1992 (source)

‘Revisiting the SPIW Pt. 1-3’, Small Arms Review, R. Blake Stevens, (123)

The SPIW The Deadliest Weapon that Never Was, R. Blake Stevens & E.C. Ezell (1985)

Our thanks to the collection that holds these wonderful examples of the ACR rifles


Please do not reproduce photographs taken by Matthew Moss without permission or credit. ©The Armourer’s Bench 2018.