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.

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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.
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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.

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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.

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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.

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

Photographs: 15 Inch Vickers Coastal Guns, Menorca

In our latest video we take a look at the massive 15 Inch Coastal Guns that protect the port of Mahon in Menorca. The guns, built by the British Vickers company, could fire an 860kg shell up to 35km.

The battery of two 15 or 381mm guns was added to the Fortalesa Isabel II’s emplacements in the early 1930s and were in active service for nearly 80 years. For more information on their history and design, check out the video and full in-depth blog here.

Below are some photographs I took of the battery and its ancillary support buildings. While researching I also found a couple of great contemporary photos.

Rear of the gun
A view of the 15 Inch Vickers Gun from the rear (Matthew Moss)
Front of gun
A view of the front of the gun turret’s housing, while not thick enough to withstand a direct hit the turret would protect against shrapnel (Matthew Moss)
View of the front of the gun
A view of the front of the gun, note the small hatch in the front of the gun housing, this would have been the gun aimer’s postion (Matthew Moss)
Ammunition crane
The sliding hatch and crane used to bring up cordite charges when the gun was in action. (Matthew Moss)
6 Inch Vickers Gun Battery
A view of the rear of one of four supporting 6 Inch Vickers guns (Matthew Moss)
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The battery’s support buildings: Stores, offices, barrack blocks(Matthew Moss)
The Battery's other 15 Inch Gun
The Battery’s other 15 Inch Gun on the other side of the old quarry that houses the battery’s support buildings (Matthew Moss
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The left side of the turret, not the ladder for roof access (Matthew Moss)

A facebook group for those who served at Fortales Isabel II has a number of brilliant contemporary photographs of the guns:

These photographs show the guns being transported by a specially laid, segmented rail track in the early 1932s, the first shows the guns at the dockside with another showing it being moved through a busy street.

The group also has some contemporary photographs of the gun emplacements including the rangefinder and the inside of the gun housing:

The gun aimer’s position with communications to the rangefinder bunkers near by:

The group also has some excellent recent photos of the restored interior of the gun turret the magazine below. The first photos show the magazine and system for bringing the 860kg shells up from the projectile store:

Sign reads: ‘Ordinary projectiles will only be used with reduced load

Great shot of the various tracks, winches and lifts used to get the massive shells up to the turret:

Interior shot of the turret with a shell ready to be winched onto the loading tray and loaded into the breech:

View of the gun aimer’s positions complete with shining brass speaking tubes and controls:

For more information on the history and design of the guns, check out the video and full in-depth blog here.


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

Hybrid Sten

 

During our first research trip last spring I had the opportunity to examine an unusual ‘hybrid’ Sten submachine gun. The weapon combined a MkII Sten’s receiver with a MkIII’s magazine housing. Added to this was a proprietary folding stock and a new fire control group and pistol grip.

Very little is known about the hybrid Sten with Peter Laidler’s book The Sten Machine Carbine mentioning it and the later Osprey book by Leroy Thompson sharing a photograph and brief caption which calls it an “experimental version of the Mk III.” It is also unclear exactly when it was built.

Below are some photographs I took of the Sten, lets look at some of the interesting features of the Hybrid Sten.

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left side of the Sten with the stock folded flush under the receiver (Matthew Moss)

No production Variant of the Sten was fitted with an under-folding stock, the Australian Austen, however, directly copied the MP38/40. The entire weapon is covered by a layer of textured, crackle paint finish, this was commonly used on commercial Sterling Mk4 submachine guns. The weapon has a short, 3.5 inch, perforated fore-end welded onto the front of the tube receiver that appears to be from a Lanchester.

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Rear right of the weapon close up of its pistol grip, stock and trigger housing (Matthew Moss)

The under folding stock is rudimentary but effective, the butt plate swivels free but the lock up is quite secure. It uses the receiver main spring-loaded return-spring cap. The folding stock attaches to the pistol grip assembly (which can be seen detached below).

The proprietary rectangular trigger group housing brazed onto the tub receiver is unlike any other Sten and lacks a fire-selector.

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Left side of the Sten with its pistol grip and stock assembly detached (Matthew Moss)

The pistol grip itself is made from paxoline, a form of early resin plastic. The shape shape of the pistol grip does not resemble any production or prototype Sten grip. A simple hand-stop, made from a bent piece of sheet metal, has also been added in front of the weapon’s ejection port to prevent the user’s hand moving back and fingers being caught if gripped by the forend.

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Right side of the Sten with its stock unfolded (Matthew Moss)

While the origins of the hybrid Sten remain unclear I don’t believe it was an officially made prototype. While impressive it is relatively crudely assembled and does not match the Sten prototypes made by Enfield, such as the VI. Intriguingly, the magazine housing of the weapon has been stamped ‘PILOT’ below the usual ‘STEN MkIII’ stamp. I suspect that the weapon may have been put together by a unit armourer, perhaps authorised by a superior officer to suggest improvements or as an unofficial project gun.

UPDATE:  Their is some evidence emerging that this Hybrid Sten may be related to the T42 Sten prototype, part of the Sten MkIV development program. Where this hybrid fits into the story is not yet clear but the similarities are striking, when we have more information we will revisit this weapon.

Technical Specifications:

Length (with stock folded): approx. 40cm (30in)
Weight: approx. 3kg (7lb)
Barrel Length: 16cm (6.5in)
Action: Blowback
Calibre: 9x19mm
Feed: 32 round box magazine
Cyclic Rate: approx. 500 rpm


Bibliography:

The Sten Machine Carbine, P. Laidler (2000)

The Sten Gun, L. Thompson (2012)


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

1958 ArmaLite AR-10 Promotional Film

In the first part of Vic’s special episode on the AR-10 we brought you a remastered version of the fascinating 1958 ArmaLite/Fairchild promotional sales film made for ArmaLite salesmen, like Sam Cummings and Jacques Michault, to show to prospective buyers of the new rifle. Back in the 1990s Vic was lucky enough to scan Michault’s copy the film and has recently remastered with better image quality.

Below you can find the video, time stamped to begin at the promotional film (although I highly recommend you watch the entire video for Vic’s introduction to the early history of the AR-10).

Lets break the video down, with the help of some screen captures. The film opens with a rifleman emerging from the sea, firing as he advances. The film then explains Fairchild’s background and beings to explain the features of the rifle.

Fairchild Armalite AR10 Promo (16).Movie_Snapshot
Arrows point out some of the AR-10s controls
Fairchild Armalite AR10 Promo (17).Movie_Snapshot
A close up of the rifle’s bolt and carrier
Fairchild Armalite AR10 Promo (20).Movie_Snapshot
A set of scales is used to demonstrate how the AR-10 (plus 50 rounds) is equal to an M1 Garand

The film then shows several shots of the rifle’s lower receiver being milled.

Fairchild Armalite AR10 Promo (4).Movie_Snapshot
The milling of the rifle’s aluminium-alloy forged receiver

None other than the rifle’s designer himself, Eugene Stoner, then takes an AR-10 from a wall display and proceeds to completely disassemble it.

Fairchild Armalite AR10 Promo (6).Movie_Snapshot
Stoner standing in front of a display board holding three AR-10 prototypes and AR-5s and an AR-7 survival rifle

Stoner completely strips the rifle, its muzzle device and its magazine before Charles Dorchester, ArmaLite’s production manager, demonstrating the rifle’s operation and subjects it to sub-zero temperatures and once again firing the rifle.

 

The film then shows the rifle being used in a variety of roles:

Fairchild Armalite AR10 Promo (26).Movie_Snapshot
AR-10 being fired with a scope mounted to the carrying handle
Fairchild Armalite AR10 Promo (27).Movie_Snapshot
The AR-10 being fired from a bi-pod in the light support role, feeding from 20-round magazines, the AR-10 LMG could easily be switched between magazine and belt feeding by removing the belt feed assembly
Fairchild Armalite AR10 Promo (28).Movie_Snapshot
An ENERGA rifle grenade being fired from the AR-10, the US Army had adopted the ENERGA as the M28 rifle grenade in 1950.

Stoner then covers the rifle with sand before running five magazines through the rifle in quick succession to demonstrate reliability:

 

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The rifle is then submerged in mud (with its dust cover closed) and demonstrated again.

Fairchild Armalite AR10 Promo (32).Movie_Snapshot
AR-10 covered in mud

The film then shows how simple field stripping and cleaning is before Stoner demonstrates the belt-fed variant of the rifle:

Fairchild Armalite AR10 Promo (41).Movie_Snapshot
A rifleman demonstrates the AR-10 in its belt-fed configuration, changing position several times before switching to feeding from magazines. Note also the ‘backpack’ belt box and controlled chute/feedway
Fairchild Armalite AR10 Promo (40).Movie_Snapshot
Stoner firing the belt-fed AR-10
Fairchild Armalite AR10 Promo (39).Movie_Snapshot
Stoner with a happy grin on his face before opening up with the AR-10,
Fairchild Armalite AR10 Promo (15).Movie_Snapshot
Note the bolt link port in the lower receiver

Don’t forget to check out the full episode and the accompanying blog here!

Photos: Heckler & Koch G11 ACR

Here are a selection of external photographs showing the H&K G11 submitted to the US Army’s Advanced Combat Rifle trials in the mid-1980s. You can watch our introductory video featuring two G11s here.

Note: While this collection of images covers only the externals of the G11, rest assured that if and when we get the opportunity we will follow this up with hi-res photographs of the weapon disassembled!  

1
Right side view of the G11, note the muzzle plug inserted into the barrel (Matthew Moss)
2
Left side view of the G11, note the small window in the magazine showing the follower spring (Matthew Moss)
3
Close up of the right side of the G11’s fire selector (safe – semi – hyperburst – full auto), trigger and grip which enclosed a ‘control brush’ used to check the chamber was empty and in cleaning (Matthew Moss)
4
Left side close up of the G11’s selector, trigger and pistol grip – note also the rifle’s designation,  serial number, presumably manufacturing date and calibre moulded into the weapon’s casing (Matthew Moss)
5
A view of the G11 from above – note the alignment of the magazine and the lack of later additional channels for spare magazines seen in some G11K2s (Matthew Moss)
6
Close up of the G11’s foregrip and sling loop and an empty magazine loaded into the weapon  (Matthew Moss)
7
Close up of the weapon’s rotating ‘cocking handle’and pressure valve, note the white arrow indicating the direction to twist the handle to cock the weapon – the plastic folding handle on this example has sadly broken off, a common issue with G11s (Matthew Moss)
8
Close up of the left side of the G11’s ‘central part’, as HK described it, into which the barrel and breech assembly slide (Matthew Moss)

Many thanks to the collection, which wishes to remain anonymous, that holds this example of the G11 for the opportunity to examine, photograph and film it.


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

Photographs: Durs Egg Breech-Loading Carbine

Matt was recently lucky enough to examine a 1785 Pattern Durs Egg Breech-loading cavalry carbine. Based upon Giuseppe Crespi’s breech-loading system, the Egg carbines were tested by British cavalry regiments in the late 1780s. You can check out our full-length article on the weapon here and our video here.

Below are a some photographs I took of the carbine showing some of the details of its design:

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A right-side view of the length of the carbine
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The carbine with its breech fully open from the right-hand, lock side
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Detail photo of the carbine’s lock and breech handle
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An overhead view of the Egg Carbine’s open breech showing the chamber into which powder and ball were placed
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A closer overhead view of the carbine’s breech
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A close up of the carbine’s spear point bayonet showing the extension of the brass trigger guard into which the bayonet point sits
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With the carbine’s breech partially open its possible to see the small touch hole into the breech block, just above the frizzen and pan, which allows the flash from the fan to ignite the powder charge
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The carbine and its bayonet

 

Our thanks to the collection that holds this example of the Durs Egg Carbine, whom wish to remain anonymous, which was kind enough to allow us access to their impressive array of small arms.


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

Photographs: BESAL

We were recently lucky enough to examine a 3rd Pattern BESAL light machine gun dating from c.1942.  You can check out our full-length article on the BESAL here and our video here.

Below are a some photographs I took of the BESAL showing some of the details of its design as well as its stamped and spot welded constriction:

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Left-side profile of the BESAL, note the shape of the butt is very similar to that of the earlier Lewis Gun
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BESAL with magazine removed, the weapon appears to use a standard MkII Bren non-adjustable bipod
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Like the Bren, the BESAL has a universal magazine adaptor to allow it to feed from both box and drum Bren magazines

Some close ups of the BESAL

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Top-down view of the BESAL note the offset sights
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Rivet reinforcement of the bolt’s locking recess in the top of the receiver
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Right side – The butt-retention pin can be seen just below the rear sight assembly, this pin is captive and once pulled allows the butt to come off, the bolt and pistol grip can then be removed from the weapon
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Close up of the BESAL’s barrel removal catch – rotate to the rear to remove the barrel
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BESAL’s spring-loaded magazine dust cover closed, note the magazine catch on the left
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A shot from behind the BESAL showing the rear sight and the enclosed front sight, both off set to the left

 

Our thanks to the collection that holds the BESAL, whom wish to remain anonymous, which was kind enough to allow us access to their impressive array of small arms.


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