Colt CGL-4 (XM148) 40mm Grenade Launcher

Here’s Vic’s video on the XM148, check out Matt’s article below:

There have been attempts to fire grenades from the infantryman’s weapon since the 17th century. Up until the 1960s these almost entirely involved muzzle attachments or grenades which could be fired off the end of a rifle’s barrel. In May 1963, the US military called for a new ‘underslung’ grenade launcher to complement the AR-15/M16, then in early testing. The grenade launcher program had its roots in the ultimately unsuccessful Special Purpose Individual Weapon (SPIW) program which had begun in 1952.

While a series of designs were developed by various manufacturers and designers, May 1964 saw Colt unveil the CGL-4. The Colt was tested against designs from Springfield Armory and Ford, a design from AAI was promising but it was not able to chamber the 40x46mm rounds used by the M79 and was rejected. The US military sought munitions commonality between the M79, already in service, and the new rifle-mounted grenade launcher.

DCC CGL-4 NO SOUND_Moment2
Left side view of the XM148’s bulky tangent sight (Vic Tuff)

In March 1965, the CGL-4 was chosen for further testing and a contract for 30 launchers was signed. The CGL-4 was reportedly developed by Karl Lewis and Robert E. Roy in just 48 days. However, the design was complex. To load the barrel housing slid forward allowing a grenade to be placed in the breech, the weapon was then cocked and a long trigger, which projected back towards the rifle’s trigger guard, could be pulled to fire the weapon.

CGL4 Patent
Karl Lewis & Robert E. Roy’s patent for the Colt CGL-4 (US Patent Office)

Despite some problems with barrel housings cracking an order for 10,500 of the new launchers, now designated the XM148, was placed in January 1966. Production capacity issues and problems with the launcher’s sight lead to production delays and it wasn’t until December 1966, that the first shipment of 1,764 launchers arrived in Vietnam for field testing.

DCC CGL-4 NO SOUND_Moment6
Right side view of the XM148’s trigger, cocking mechanism and pistol grip (Vic Tuff)

Initial reports from the field were promising with troops praising the “tactical advantage of both the point fire and area fire system” concept. The XM148 was well received by the SEALs and the Australian SAS. The armourers of the Australian SAS, deployed to Vietnam with the 1st Australian Task Force, were also hard at work attaching XM148s to L1A1 rifles. Removing the L1A1′s handguard and attaching the XM148 to the rifle’s barrel.

Field testing was carried out by 12 units from six different divisions which were operating in various parts of Vietnam. This gave a wide variety of terrains and yielded some interesting results. In general it was found that the XM148 decreased rate and quantity of the grenadier’s fire, it slowed his reaction times when firing at a target, it hampered his movement in dense vegetation and also meant the grenadier had to spend longer caring for his weapon.

DCC CGL-4 NO SOUND_Moment4
XM148 with breech open (Vic Tuff)

It was noted that the sight mount which was overly complex and prone to snagging on brush and kit, it was also felt that too much force was needed to cock the XM148 (around 30 lbs) and the trigger mechanism was felt to be overly complex and difficult to repair and disassemble. One safety concern was the XM148′s long trigger bar, which could snag and launch a round – not ideal for special forces patrols infiltrating through thick bush. Problems with the launcher’s quadrant sights also continued causing deflection errors out at longer ranges. The bulkiness of the sights exasperated these problems as when they were knocked the XM148′s zero could be effected. The XM148 also precluded the use of a bayonet as when fired it would blow the bayonet off the muzzle. Overall, troops felt the XM148 was too fragile and complex for use in the field.

XM148 in vietnam
SP4 Willey firing an M16A1 mounted with a Colt XM148 c. 1967 (US National Archives)

At least one unit found use for the launchers, the 1st Cavalry Division (Airmobile)’s Operational Report for Quarterly Period Ending 31 October 1967, noted that the XM148

“proved unsatisfactory in infantry units due to its lack of durability; consequently, USARV directed that they be turned in. However, 1/9 Cav has devised a method of mounting the launcher coaxially on the M60C machine gun used by scout observers on OH-13 scout helicopters. Durability in this environment is
not a problem since the weapon deos not receive the rough handling it did in the hands of ground troops. Firepower on scout helicopters is significantly increased. Fifty-two XM148s have been retained for use by 1/9 CAV.”

Finally, despite Colt’s efforts to rectify the growing list of problems the Army Concept Team In Vietnam deemed the XM148 unsatisfactory for deployment in Vietnam and recommended they be removed from service and a new improved launcher be developed. This was a massive blow to Colt who had already manufactured 27,400 XM148s. Many of these were already in Vietnam.

The US Army launched the Grenade Launcher Attachment Development (GLAD) program in the summer of 1967. A large number of manufacturers submitted designs including Colt, who offered the improved Henry Into-designed CGL-5. The Army turned down Colt’s offer of 20 free improved launchers and rejected the CGL-5 outright. The GLAD program saw the resurgence of the earlier AAI design, designated the XM203, this simple design, now chambering the 40x46mm shell, was eventually selected in August 1968. Ironically, as AAI was predominantly a research and development company and after an initial run of 10,000 made by AAI, Colt was subsequently awarded the contract to manufacture the M203 from 1971 onwards.

CGL-5
Harold Into’s patent for the product improved CGL-5 (US Patent Office)

While the XM148 proved to be a failure it played an important role in proving the operational viability of the rifle mounted grenade launcher system. The muzzle-launched rifle grenade is all but obsolete, superseded by the under-slung grenade launcher.

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


Specifications:

Length: 16.5 inches
Weight: ~3lbs
Calibre: 40x46mm
Action: single shot, striker-fired single action
Capacity: 1
Rate of Fire: ~4 rpm


Bibliography

Images: 1 2 3 4 5 6

Black Rifle, E.C. Ezell & R. Blake Stevens, (1987)

Colt Industries Newsletter, Vol.2 no.3, May 1967, (source)

‘Grenade launcher having a rotatable forwardly sliding barrel and removable firing mechanism’, US Patent #3507067, H.A. Into, 14/12/67 (source)

Operational Report for Quarterly Period Ending 31 October 1967, 1st Cavalry Division (Airmobile), (source)

‘Grenade launcher’, US Patent #3279114, K. Lewis & R. Roy, 25/09/64 (source)

Springfield Armory Database entries: 1 2 3

40mm Shoulder-Fired Grenade Launchers & the SEALS, Small Arms Review, K. Dockery, (source)

The XM148: Birth of the Mounted 40mm Grenade Launcher, Small Arms Review, J. Wong, (source)

My thanks to Daniel Watters for information on AAI & Colt M203 production contracts. 

The CETME AMELI Light Machine Gun

The CETME AMELI was developed by Spain’s state-owned small arms institute, Centro de Estudios Técnicos de Materiales Especiales or CETME. It was an attempt to develop a light machine gun chambered in 5.56x45mm. Its name, AMELI, is an acronym for ‘Ametralladora ligera’ – simply Spanish for light machine gun.

Development of the AMELI began in 1974 under the supervision of Colonel José María Jiménez Alfaro (who would later become the director of CETME). The Ameli was officially unveiled in 1981 and after undergoing exhaustive military trials was adopted into service in 1982 as the standard squad-level support weapon of the Spanish Army under the designation MG 82. It was manufactured by the Santa Bárbara National Company (now General Dynamics Santa Bárbara Sistemas) at the La Coruña factory.

Centrefire automatic machine gun - CETME Ameli (about 1982) (1)
Early NA or standard model AMELI (Royal Armouries)

The initial model was the NA variant, or Standard Model. This is the model that closely resembles the MG-42 with its conical flash hider. The Spanish military, however, wanted a lighter gun and the NB variant was designed, this is easily identified by the straight flash hider that is now integral with the barrel and not part of the barrel shroud.  The NB model reduced the unloaded weight from the original 7.24 Kg (16 lbs) to 5.4 Kg (12 lbs). However, this weight reduction and the use of materials of lower cost than the original trialled guns caused reliability issues with the AMELI in service. Both variants had a rotating rear disk sight, graduated from 300 to 1,000 metres, and a folding front sight. A mounting block for a British SUSAT optic was later added to the top cover.

Ameli with Winter Trigger Group
Detail view of the AMELI’s receiver from a factory brochure, also featuring the transparent belt boxes which did not go into service (source)

Parts breakages and stoppages plagued the AMELI in service and gunners had to take great care of their weapons to keep them serviceable. One issue was that the stamped forward barrel shroud was a press fit over the receiver and held in place by steel ‘barbs’. Rough handling and downward pressure on the bipod during manoeuvres and firing caused the shroud to deflect, this caused accuracy and functionality issues. To alleviate these problems the Spanish Marines went so far as to TIG weld the forward barrel shroud to the receiver, this fixed most of those issues.

The AMELI’s shape resembles the MG42 machine gun but the similarities are external only. While the MG42 uses the short recoil, roller locked system (where the barrel and bolt recoil together a short distance before separating), the AMELI employs a roller-delayed blowback action with a fixed barrel and a fluted chamber. This system was also used in the CETME Model A, B, C and L rifles, as well as in the HK G3 rifle, the HK 33 rifle and the HK MP5 submachine guns. Similarities with the CETME Model C and Model L rifles are limited to the commonality of the takedown pins and no other parts contrary to popular myth!

Centrefire automatic machine gun - CETME Ameli (about 1982)
Later NB variant of the AMELI – note also the different pistol grip profile, more similar to a CETME L rifle’s (Royal Armouries)

Both AMELI models have similar rates of firing of around 1,000 rounds per minute. The AMELI used the same feeding system used in the MG42, it had a cross bolt safety located at the rear of the top of the pistol grip and a quick change barrel system. To remove the barrel you pull the two sides of the barrel latch, which is built into the rear sight assembly, rotate the handle clockwise until the gate in the side of the barrel shroud opens and then pull the barrel back out of the gun. The front of the barrel is secured by a round ball detent which clicks into the front of the barrel shroud.

CETME also developed a top feeding magazine adaptor system, perhaps inspired by the contemporary FN Minimi’s ability to feed from magazines as well as a bolt. The Bren-like adaptor allows a STANAG magazine to be loaded in upside down into the action. To fit the adaptor the gun’s top cover and feed tray had to be removed. To deal with the magazine housing now obscuring the front sight the adaptor had a new set of sights – one at the rear and a new ‘front’ sight built into the side of the magazine housing, a little like the Australian F1 submachine gun. This short sight radius isn’t too practical for a light machine gun.

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A still from the video showing the top feed magazine adaptor’s sights, note they’re offset to the right and the protected front sight is built into the magazine housing (Vic Tuff)

The AMELI was sold to only a few operators apart from the Spanish Military, the Mexican Army and the Malaysian PASKAL Naval Special Forces have used the AMELI but the current status with those operators is unknown. In Spanish service the Ameli has almost entirely been withdrawn from service, being replaced with the Heckler & Koch MG4 5.56x45mm LMG. This is partly due to reliability issues and the original guns being worn out and with spares and new guns no longer available as the original manufacturer ceased manufacture in 2013 and went out of business.

Mexican Army Ameli
Mexican Marines with an NA model AMELI (source)

The AMELI is an interesting machine gun that should have had more success than it did. It was sadly a victim of government cost cutting which much like the British SA80 undermined the quality of the finished product. The story of the AMELI also reminds me of the ArmaLite AR10 produced by Artilleries Inrichtingen in the Netherlands, in so much as the AMELI was produced in very limited numbers (around 3-4,000 guns), in various models and variants with no clear defined history as to why aspects of the design were changed. Evidence of this was seen when a very good contact of mine bought up all remaining inventory from the CETME factory some years ago including around 30 Ameli’s. Apparently there were variations between every one they bought!

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


Specifications (from CETME brochure):

Length: 97cm (38.2 inches)
Weight (unloaded):  NG: 6.7kg (14.8 lbs) NB: 5.2kg (11.5 lbs)
Barrel Length: 40cm (15.8 inches)
Action: Roller-delayed blowback
Calibre: 5.56x45mm
Feed: 100 or 200 round belts
Cyclic Rate: 900-1,250 rpm


Bibliography:

CETME AMELI Operator’s Manual, Small Arms Review Archive, (source)

CETME AMELI Early Factory Brochure (Spanish), Small Arms Review Archive, (source)

CETME AMELI Factory Brochure – including both models (English), Small Arms Review Archive, (source)

CETME AMELI Factory Flyer (Spanish), Small Arms Review Archive, (source)

 

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