By Seth R. Nadel
It may come as a surprise to many, but the Direct Gas Impingement (DGI) system has a long and storied history. No, Eugene Stoner did not invent it, nor was the AR-15/M16 the first service rifle to employ it. It’s a tale that starts in France, runs up to Sweden, down to Egypt, back to France, and then ends up with what is, arguably, the world’s most popular service rifle.
As explained in Jean Huon’s outstanding book, Proud Promise (Collector Grade Publications), DGI made its first known appearance in France, in 1900. A weapons inspector named Rossignol placed a gas tube on the right side of a straight pull rifle he had designed in 1896, and the DGI system worked. But it was not adopted by the French army, and for years it was on the fringes of their rifle development while they followed other paths.
In effect, what Rossignol did was to lengthen the ‘usual’ gas tube, as found on our M1 rifle, and use the bolt carrier as the piston. Tubes are always lighter than rods (as in operating rods), so he completely changed the weight and balance of a rifle.
DGI did resurface in French test rifles in 1901, 1912, 1922, 1926, 1928, 1931, and 1939. With each new version, function improved, but for a variety of reasons, financial, tactical, and logistical among others, it was not fully adopted. A few M1940 rifles made their way into the hands of troops, but there is no record of their use in combat. Naturally, WWII virtually stopped all non-German rifle development in Europe.
The Ljungman
In 1942, the neutral Swedes became the first country to adopt a DGI rifle. The AG 42 B moved the gas tube from the right side to the top of the barrel. It was in 6.5x55 caliber, and never fully replaced the various bolt-action rifles in use in that caliber. It was replaced in 1965 by the German G3 (HK 91) rifle, so it too was not known to be used in combat.
A large, (47.8 in), heavy (10.4 lb) traditional style rifle, it has some unique characteristics such as an in-drilled muzzle with a series of holes from 8 o’clock to 4 o’clock to act as a muzzle brake although a ten pound rifle in 6.5x55 perhaps could have done without a muzzle brake. The gas port is approximately 10 inches back from the muzzle.
Since there were both round-nose and Spitzer rounds in service, the rear sight can be reversed by the user to account for the differing drop of the two rounds. The rear sight is controlled for elevation by a drum, while windage changes are made in the front sight with a screw.
Perhaps the oddest change is the manual of arms as there is no obvious bolt handle. The rear receiver cover has two ‘horns,’ however. By grasping the horns the cover can be moved forward where it captures the bolt carrier and can draw it to the rear. If the safety is off, when the bolt/bolt carrier reaches the rear of the receiver, the bolt slams forward, chambering a round. If the safety, a lever at the rear of the receiver, is on, the bolt stays to the rear.
The rear receiver cover is equipped with a stripper clip guide for recharging the 10-round magazine, as well as a large rubber ‘roller’ to reduce damage to the cases as they are ejected. Stripper clip recharging of the magazine on the gun remained in place on all the other DGI rifles, until the AR series.
The trigger guard is somewhat oval to ease use with gloves and the rear sling swivel is offset to the left and located just behind the pistol grip. The forward sling swivel is on the left of the rifle, and they are seen in photos slung diagonally across the back of the Swedish troops.
The magazine is unique, as there is the usual release on the rifle to the rear, but also some additional retention. The front of the magazine is equipped with a spring with hooks on either side, which engage into the front of the magazine well. Evidently, there had been a problem with lost magazines, and this was the solution.
Finally, there is a brass plate inlet into the left side of the stock - but this is not for unit markings. It is used to show the bore wear on the rifle: the Swedes like to be accurate.
All in all, the Ljungman is a fairly typical post war semi-auto rifle, other than its use of the Rossignol gas system.
The Hakim & Rasheed
Circa 1949, Swedish engineers set up a rifle plant in Egypt (then known as the United Arab Republic or UAR). The plant made a redesigned Ljungman, still using the DGI system, but with some differences. The caliber came up to 7.92 (8mm Mauser).
The muzzle brake is much larger, with more holes and a pair of large ports to either side, which seems more appropriate on an 8mm rifle. The sling loops retain their position on the left side (front) and angled to the left behind the pistol grip. The rear sight is a simple tangent, marked (in Egyptian) to a realistic 1,000 yards, rather than the more complex Swedish drum.
A most unusual change is the triangular lever on top of the gas tube about one foot back from the front sight. With the correct tool, this can be used to adjust the DGI gas system. Having fired some Egyptian ammunition, it was somewhat ‘uneven’ in quality. And the sands of a desert can slow or stop a rifle’s action.
The magazine does without the front retention spring and also holds 10 rounds. Oddly, the finger lever for the magazine release folds flat against the lower receiver. The receiver cover carries out all the functions as on the Ljungman, using pads of grooves rather than the more glove friendly horns. The rubber case deflector roller has been replaced with a large steel loop, looking like an enlarged sling loop.
Beretta is reported to have made a .22 caliber training rifle for the Hakim, and Anschutz made an air rifle version, both for the Egyptian Army. Either is quite rare these days.
In the mid-1950s, Russia obtained a lot of influence in Egypt and the Egyptians obtained a number of SKS carbines in 7.62x39. Appreciating the carbine length and intermediate cartridge, they blended the Hakim operating system with the round to produce the Rasheed.
Smaller (41.5 inches) and lighter, they kept the general stock pattern and adjustable DGI gas system. But the rear cover is only that; with an operating handle on the right side. The rear sight adjusts to 900 yards. The muzzle brake is gone and replaced with a knurled muzzle nut. An under-folding blade bayonet has been added, along with ventilating ports in the upper hand guard.
The Rasheed is a slightly heavy SKS replacement, still with a detachable 10-round magazine that can be recharged while on the rifle. Very few Rasheeds were made, as the ubiquitous AK47 soon replaced it in Egyptian service.
The French 49-56
Although the precise timing is murky, the final iteration of a DGI service rifle before Eugene Stoner’s creation is the French M1949-56. Slightly shorter than the contemporary Rasheed at 40.5 inches, it’s not clear which one was adopted first. Initially, the M1949 was produced in very limited numbers as the Government could not make a decision with so many surplus arms available. After 20,600 were made, it was upgraded to the Model 49-56, and widely issued. Clearly, with the long French history of working on the DGI system, this is the most refined of the DGI rifles. Originally issued in the French 7.5mm round, after they joined NATO the guns were made (and marked) in 7.62 - some examples are also marked “308” under the 7.62.
The 49-56 is about the most versatile rifle made prior to the AR-15/M16 series. Every rifle was equipped with a muzzle grenade launcher. Raising the grenade launching sight requires cutting off the gas supply to operate the rifle. This spares the system the stress of overpressure, while allowing all the gas to be used to propel the grenade. Two different rubber recoil pads were issued, long and short, to reduce stock breakage when firing rifle grenades. Make no mistake; launching grenades was NOT done from the shoulder. Generally, the butt was placed on the ground when a grenade was fitted. If it had to be fired hand-held, the stock was to be placed under the arm, to reduce injury. Beyond the grenade launcher is a muzzle brake. While the 49-56 is weighty at 9.9 pounds, it is also relatively short, so a muzzle brake would tend to soften recoil.
Realizing that combat was moving into the realm of night action, the French issued a slip-on set of night sights. This takes the form of a tube, large enough to fit over the grenade launcher and muzzle break, with large sections cut away to allow the gases from the brake to vent, and to act as a flash hider. The tube is held on with a wing nut, and bears luminous front and rear sights. The sights can be adjusted by loosening screws. One unique feature of the sights is their color. They look beige in daylight, but in the dark, after being ‘charged’ with a flash light, the front sight is green while the dots on the rear sight are amber. The sights were claimed to be useful for aimed fire to 100 meters.
Every 49-56 has a groove milled into the left side of the receiver to accept the telescopic sight or early night vision sight. A special 4 power scope was used on the rifle, but it is unlikely that a rifle subjected to the stress of launching grenades would still be accurate enough for use as a sniper rifle.
One feature unique to the 49 and 49-56 is the placement of the magazine release - it is on the magazine. The right side of the magazine bears a spring powered lever ending in a claw. The receiver has a small divot, where the claw grips. It is an unusual but effective system.
The 49-56 was used in Indochina (Viet Nam), prior to the US involvement. It was well liked, albeit a bit heavy and ’chunky.’ With its prior service in Algeria, the 49-56 is the most ’combat proven’ of the pre-AR DGI rifles. It was replaced in 1972 by the 5.56 FAMAS rifle, and the DGI system finally left the French service.
If Eugene Stoner did not ‘invent’ the DGI system, what, exactly, did he do? To my mind, he deserves tremendous credit for three innovations:
1. Introducing the manufacture of rifles using aluminum and polymers, rather than wood and steel. While critical parts of the AR-15/M16 are made of steel, the great volume of the rifle is made of light weight, easy to mold and machine aluminum, and moldable polymers. Called ‘space age’ at the time, we have yet to find a better combination.
2. Combining the Rossignol gas system into an expanding interior gas pressure space, with a multi-lugged rotating bolt in an imaginative, creative way. The AR design has been produced in more places, by more makers, in more calibers, than any other rifle.
3. Applying ergonomics - the shape of the shooter’s hands and body - into the design of a lightweight, selective fire rifle. The features were projected in 1942 by Melvin Johnson, designer of the Johnson rifle and light machine guns. In his book, Weapons for the Future, he forecast that in the future our fighting rifle would be a small bore (smaller than .30 cal.) with a straight line stock, with the sights mounted high above the bore. His own rifle, while a .30-06, embodied some of these principals and his light machine gun had both the straight line stock and the high sights.
But it was Stoner’s placement of the safety/selector, magazine release, and pistol grip that set the standard for comparison for all shoulder arms right up to today.
For these three advances, but particularly for the last, the application of ergonomics to firearms design, Eugene Stoner deserves every plaudit and recognition. From here, who knows what will be next? Even Stoner’s team developed a gas piston rifle, which became the AR-18/180. But until a better system of ergonomics comes along, the AR design of control placement shall be the standard, in all calibers, direct gas impingement or not.
This article first appeared in SmallArmsReview.com on July 12, 2013 |
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