The Armourer’s Bench are proud to introduce our very first ‘informative colouring (coloring) book’. Not only can you colour in the prototypes from the US Army’s Advanced Combat Rifle trials but you can also learn about the guns, how they worked, performed and the outcome of the trial as you colour!
Why a colouring book? Well, simply put, no one else has done one before! With the help of our brilliant illustrator, Lauren McInnerney, we put the book together to give you guys something a bit different, something fun!
We have a limited run of these little books and we will do our very best to get them our ASAP if you order them for Christmas.
The book includes detailed original illustrations of each of the four ACR guns: the AAI, Colt, Steyr and of course the iconic HK G11. The 8-page booklets are 8×6″ (or A5 sized) and are available now from our website for $6.00, plus shipping.
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.
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.
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.
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.
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.
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.
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