The M3 Lee Medium Tank, M3, was an American medium tank used during World War II. In Britain, the tank was called by two names based on the turret crew size. Tanks employing US pattern turrets were called the "Lee", named after Confederate general Robert E. Lee. Variants using British pattern turrets were known as "Grant", named after Union general Ulysses S. Grant. Design commenced in July 1940, the first M3s were operational in late 1941; the U. S. Army needed a medium tank armed with a 75mm gun and, coupled with the United Kingdom's immediate demand for 3,650 medium tanks, the Lee began production by late 1940; the design was a compromise meant to produce a tank as soon as possible. The M3 had considerable firepower and good armor, but had serious drawbacks in its general design and shape, including a high silhouette, an archaic sponson mounting of the main gun preventing the tank from taking a hull-down position, riveted construction, poor off-road performance, its overall performance was not satisfactory and the tank was withdrawn from combat in most theaters as soon as the M4 Sherman tank became available in larger numbers.
In spite of this, it was considered by Hans von Luck to be superior to the best German tank at the time of its introduction, the Panzer IV. Despite being replaced elsewhere, the British continued to use M3s in combat against the Japanese in southeast Asia until 1945. Nearly a thousand M3s were supplied to the Soviet military under Lend-Lease between 1941–1943; the M3 Lee was the medium tank counterpart of the light tank M3 Stuart. In 1939, the U. S. Army possessed 400 tanks M2 Light Tanks, with 18 of the to-be-discontinued M2 Medium Tanks as the only ones considered "modern"; the U. S. funded tank development poorly during the interwar years, had little experience in design as well as poor doctrine to guide design efforts. The M2 Medium Tank was typical of armored fighting vehicles many nations produced in 1939; when the U. S. entered the war, the M2 design was obsolete with a 37 mm gun, an impractical number of secondary machine guns, a high silhouette, 32 mm frontal armor. The Panzer III and Panzer IV's success in the French campaign led the U.
S. Army to order a new medium tank armed with a 75 mm gun in a turret as a response; this would be the M4 Sherman. Until the Sherman reached production, an interim design with a 75 mm gun was urgently needed; the M3 was the solution. The design was unusual because the main weapon – a larger caliber, medium-velocity 75 mm gun – was in an offset sponson mounted in the hull with limited traverse; the sponson mount was necessary because, at the time, American tank plants did not have the design experience necessary to make a gun turret capable of holding a 75 mm weapon. A small turret with a lighter, high-velocity 37 mm gun sat on top of the tall hull. A small cupola on top of the turret held a machine gun; the use of two main guns was seen on the French Char B1 and the Mark I version of the British Churchill tank. In each case, two weapons were mounted to give the tanks adequate capability in firing both anti-personnel high explosive and canister ammunition and armor-piercing ammunition for anti-tank combat.
The M3 differed from this pattern, having a main gun that could fire an armor-piercing projectile at a velocity high enough for piercing armor, as well as deliver a high-explosive shell, large enough to be effective. Using a hull mounted gun, the M3 design could be produced faster than a tank featuring a turreted gun, it was understood that the M3 design was flawed. A drawback of the sponson mount was that the M3 could not take a hull-down position and use its 75 mm gun at the same time; the M3 was tall and roomy: the power transmission ran through the crew compartment under the turret basket to the gearbox driving the front sprockets. Steering was by differential braking, with a turning circle of 37 ft; the vertical volute-sprung suspension units possessed a return roller mounted directly atop the main housing of each of the six suspension units, designed as self-contained and replaced modular units bolted to the hull sides. The turret was power-traversed by an electro-hydraulic system in the form of an electric motor providing the pressure for the hydraulic motor.
This rotated the turret in 15 seconds. Control was from a spade grip on the gun; the same motor provided pressure for the gun stabilizing system. The 75 mm gun was operated by a loader; the periscope rotated with the gun. The sight was marked from zero to 3,000 yd, with vertical markings to aid deflection shooting at a moving target; the gunner laid the gun on target through geared handwheels for elevation. The shorter barreled 75 mm M2 cannon sometimes featured a counterweight at the end of the barrel to balance the gun for operation with the gyrostabilizer until the longer 75 mm M3 variant was brought into use; the 37 mm gun was aimed through the M2 periscope, mounted in the mantlet to the side of the gun. It sighted the coaxial machine gun. Two range scales were provided: 0–1,500 yd for the 37 mm and 0–1,000 yd for the machine gun; the 37 mm gun featured a counterweight – a long rod under the barrel – though it was ill maintained by crews who knew little about its use. There were two.30-06 Browning M1919A4 machine guns mounted in the hull, fixed in traverse but adjustable in elevation, which were controlled by the driver.
These were, due to coordination issues, though th
MGR-1 Honest John
The MGR-1 Honest John rocket was the first nuclear-capable surface-to-surface rocket in the United States arsenal. Designated Artillery Rocket XM31, the first unit was tested on 29 June 1951, with the first production rounds delivered in January 1953, its designation was changed to M31 in September 1953. The first Army units received their rockets by year's end and Honest John battalions were deployed in Europe in early 1954. Alternatively, the rocket was capable of carrying an ordinary high-explosive warhead weighing 1,500 pounds. Developed at Redstone Arsenal, the Honest John was a large but simple fin-stabilized, unguided artillery rocket weighing 5,820 pounds in its initial M31 nuclear-armed version. Mounted on the back of a truck, the rocket was aimed in much the same way as a cannon and fired up an elevated ramp, igniting four small spin rockets as it cleared the end of the ramp; the M31 had a range of 15.4 miles with a 20 kiloton nuclear warhead and was capable of carrying a 1,500-pound conventional warhead.
The M31 system included a truck-mounted, solid-fueled rocket transported in three separate parts. The Honest John was assembled in the field before launch, mounted on an M289 launcher, aimed and fired in about 5 minutes; the rocket was outfitted with a W7 nuclear warhead, with a variable yield of up to 20 kilotons of TNT. There was a W31 variant of 20 kt used for the Nike Hercules anti-aircraft system; the M31 had a range between 15.4 mi. Early tests exhibited more scatter on target than was acceptable when carrying conventional payloads. Development of an upgraded Honest John, M50, was undertaken to extend range; the size of the fins was reduced to eliminate weathercocking. Increased spin was applied to restore the positive stability margin, lost when fin size was reduced; the improved M50, with the smaller fins and more "rifling", had a maximum range of 30+ miles with a scatter on target of only 250 yards, demonstrating an accuracy approaching that of tube artillery. The Honest John was manufactured by the Douglas Aircraft Company of California.
In the 1960's, sarin nerve gas cluster munitions were available, designed to be interchangeable for use with either the Honest John or MGM-5 Corporal. The M79 GB cluster warhead, containing 356 M134 bomblets for the M31A1C Honest John; the production model was the M190 GB cluster warhead, containing 356 M139 bomblets when the M31A1C was phased out in favor of the XM50 Honest John. Under nominal conditions it had an mean area of effect of 0.9 square kilometers. The two basic versions of Honest John were: MGR-1A was 27 feet 3 inches long, had an engine diameter of 22.875 inches, a warhead diameter of 30 inches, a span of 104 inches, weighed 5,820 pounds, had a maximum range of 15.4 miles. The Hercules Powder Company X-202 rocket motor was 197.44 inches long, weighed 3,937 pounds, had 90,325 lbf average thrust. MGR-1B was 24 feet 10.53 inches long, had an engine diameter of 22.8 inches, a warhead diameter of 30 inches, a span of 56 inches, weighed 4,332 pounds, had twice the range of the M31. An improved propellant formulation gave the rocket motor 150,000 lbf thrust.
Production of the MGR-1 variants finished in 1965, with a total production run of more than 7,000 rockets. The Honest John's bulbous nose and distinctive truck-mounted launch ramp made it an recognized symbol of the Cold War at army bases worldwide and National Guard armories in the U. S.. Though it was unguided and the first U. S. nuclear ballistic missile, it had a longer service life than all other U. S. ballistic missiles except the Minuteman system. The system was replaced with the MGM-52 Lance missile in 1973, but was deployed with the National Guard units in the United States as late as 1983. Conventionally armed Honest Johns remained in the arsenals of Greece and South Korea until at least the late 1990's. By the time the last Honest Johns were withdrawn from Europe in the late'80's, the rocket had served with the military forces of Belgium, Canada, France, Greece, the Netherlands, South Korea and Turkey. In late 1950, Major General Holger Toftoy was a colonel overseeing the development of the rocket.
The project was in danger of cancellation "on the grounds that such a large unguided rocket could not have had the accuracy to justify further funds." On a trip to White Sands Missile Range, Toftoy met a Texan man, prone to making unbelievable statements. Whenever anyone expressed doubt about the man's claims, he would respond, "Why, around these parts, I'm called'Honest John!'" Because the project was being questioned, Toftoy felt that the nickname was appropriate for the rocket and suggested the name to his superiors. Vehicles used with the Honest John platform: M33 trailer, launcher, M46 truck and tie down unit M289 truck, rocket launcher, M329 trailer, rocket transporter, M386 Truck, Rocket, 762mm, short launch rail, 5-ton M405 handling unit, trailer mounted, M465 cart assembly, transport, 762mm rocket, Canada CFB Petawawa Military Museum, CFB Petawawa, Ontario; the Central Museum of The Royal Regiment of Canadian Artillery, Shilo ManitobaDenmark The Royal Danish Arsenal M
The Suomi KP/-31 was a submachine gun of Finnish design used during World War II. It was a descendant of the M-22 prototype and the KP/-26 production model, revealed to the public in 1925; the Suomi-konepistooli KP/-31 is abbreviated to Suomi KP. The Suomi KP/-31 is regarded by many as one of the most successful submachine guns of World War II the soon developed 71-round drum magazine was copied and adopted by the Soviets for their PPD-40 and PPSh-41 submachine guns; the accuracy of the Suomi was superior to that of the mass-produced PPSh-41, thanks in part to a noticeably longer barrel, with the same rate of fire and the large magazine capacity. The major disadvantage of the Suomi KP/-31 was its high production cost, which led to the production of the KP/-44, identical to the Russian PPS-43, but accepted the existing magazines and drums for the KP/-31; the M-22 and KP/-26 were made by Konepistooli Oy, founded by Master Armorer Aimo Lahti, Captain V. Korpela, Lieutenant Y. Koskinen and Lieutenant L. Boyer-Spoof.
The Suomi KP / -31 was designed by Lahti. The Suomi KP/-31 went into serial production in 1931 by Tikkakoski Oy and most of these weapons were bought by the Finnish Defence Forces; the Finnish Defence Forces were equipped with about 4000 Suomi KP/-31 submachine guns when the Winter War started. During the course of the war, the design was altered in February of 1942 with the addition of a muzzle brake, which increased the submachine gun's overall length by 55 mm and weight by half a pound; the revised version was designated KP/-31 SJR. Aimo Lahti was displeased with this revision, believing that it decreased muzzle velocity and reduced the weapon's reliability, sought in vain to have the unknown muzzle brake's designer court-martialed. Half of the KP/-31s in Finnish service were of the SJR version; the KP/-31 was unusual in that it had a replaceable barrel secured with four lugs rather than threads. Soldiers were issued at least one spare barrel. In close combat the weapon would overheat in sustained automatic fire, requiring the barrel to be changed.
This was effected using a mitten or piece of thick cloth to secure and remove the barrel jacket. The user would use the point of a puukko knife or a cleaning rod to loosen and remove the hot barrel, it was easy to slide in and lock a fresh new barrel, secure the jacket, resume firing. The Finnish military issued it with the 20-round staggered-column magazine and early 40-round sissilipas drum; the magazine's capacity was found to be too small for sustained fire. Up to 5 additional rounds could be loaded into it, but it was found that this damaged or over-compressed the springs and caused it to fail; the drum was found to be hard to reload in action because the backplate had to be taken off and the bullets loaded inside. The drum had an open "shot count window" in the bottom of the drum. However, it let in dirt and debris that led to jams. Aimo Lahti experimented with a 60-round Thompson-type spring-loaded clockwork drum to replace it, but it was never adopted, they were replaced during the Continuation War with the Swedish-designed 50-round "coffin" magazine and improved 71-round drum.
The "coffin" magazine carried more ammunition than the box magazine and was lighter than the 40-round drum. However, it was complicated and prone to jamming or failure if it was damaged, reassembled incorrectly, or the springs gave out, it would fail to fire or feed unless it was properly seated in the magazine well. The "coffin" magazine was withdrawn from service in 1943 in favor of the 71-round drum; the larger drum was a design by the weapon's less-well-known co-designer, Lieutenant Y. Koskinen, an improvement of the 40-round drum, it had a removable front-plate, quicker to reassemble and was cocked by rotating the mainspring for up to four detents, allowing the drum to be reloaded. It was first released commercially in 1935 and entered into Finnish service in January, 1936, it was so reliable and successful that the design was reverse-engineered by the Russians for their 7.62mm PPSh-41 submachine gun. In the 1950s the magazine wells on the KP/-31s were modified in order to use the Swedish Carl Gustav m/45b's 36-round double-column magazine.
The KP/-31 was issued as a substitute for a light machine gun, proved inadequate in this role. Instead, soldiers learned by error how to use submachine guns to the best effect. By the time of the Continuation War, Finnish doctrine had been altered to include both a KP/-31 and a light machine gun in every infantry squad. By 1943 this had been expanded to two KP/-31s per squad. KP/-31 production continued with the intention of adding a third submachine gun to each squad, but this plan was shelved in 1944 when the Continuation War ended. Finland focused on sales to the Baltic States, it was sold to both sides during the Spanish Civil War. Estonia and Poland bought some before World War Two that were captured. Germany and their Axis allies Bulgaria and Croatia bought some after the war began; the German Armeeoberkommando Norwegen and Finnish SS Troops were issued the KP/-31 from Finnish stores. A weld-on magazine adapter was created by the Germans to convert MP38/MP40 magazines to feed in the KP/-31 to simplify logistics.
The Suomi KP was manufactured under licen
The Hume Highway, inclusive of the sections now known as the Hume Freeway and Hume Motorway, is one of Australia's major inter-city national highways, running for 840 kilometres between Melbourne in the southwest and Sydney in the northeast. Upgrading of the route from Sydney's outskirts to Melbourne's outskirts to dual carriageway was completed on 7 August 2013. From north to south, the road is called the Hume Highway in metropolitan Sydney, the Hume Motorway between Prestons and Berrima, the Hume Highway elsewhere in New South Wales and the Hume Freeway in Victoria, it is part of the Auslink National Network and is a vital link for road freight to transport goods to and from the two cities as well as serving Albury-Wodonga and Canberra. The main alternative route between Sydney and Melbourne is the Princes Highway/Princes Freeway/Princes Motorway route which follows the coast for most of its length. Other inland alternate routes include the Olympic Highway route between Albury and Sydney via Wagga Wagga and Bathurst, the Federal Highway / Monaro Highway route via Canberra which links with the Hume Highway near Goulburn and the Princes Highway in East Gippsland.
In New South Wales during 2013, the National Highway shield, National Highway 31, was replaced with a standard alphanumeric route number, the M31 south of Prestons. This re-numbering for the first time in over 20 years created one continuously signed route along the Hume Highway, having been signed the M31 in Victoria during the 1990s. During 2013, the route between Berrima and Prestons was renamed the Hume Motorway; the coast of New South Wales from the Queensland border to the Victorian border is separated from the inland by an escarpment, forming the eastern edge of the Great Dividing Range. There are few easy routes up this escarpment. To climb from the coast to the tablelands the Hume Highway uses the Bargo Ramp, a geological feature which provides one of the few easy crossings of the escarpment. In the first twenty years of European settlement at Sydney, exploration southwest of Sydney was slow; this area was wooded at the time the "Bargo brush", regarded as impenetrable. In 1798 explorers reached the Moss Vale and Marulan districts.
Any settlement would have to await the construction of an adequate access track, which would have been beyond the colony's resources at the time, would have served little purpose as a source of supplies for Sydney, due to the time taken to reach Sydney. In 1804, Charles Throsby penetrated through the Bargo brush to the country on the tablelands near Moss Vale and Sutton Forest. On another expedition in 1818, he reached Lake Bathurst and the "Goulburn Plains". Many of the early explorers would most have used aboriginal guides, but they do not appear to have given them credit. After Charles Throsby's 1818 journey towards present day Goulburn, followed by Hamilton Hume and William Hovell's overland journey from Appin to Port Phillip and return in 1824, development of the Southern Tablelands for agriculture was rapid; the present route of the Hume Highway is much the same as that used by the pioneers. The route taken by the Hume Highway to climb from the coast to the Southern Tablelands and thence across the Great Divide is situated between the parallel river gorge systems of the Wollondilly and Shoalhaven rivers.
This country consists of a sloping plateau, dissected by the Nepean River and its tributaries. The route of the Highway, by using four high-level bridges to cross these gorges, avoids the Razorback Range, has minimal earthworks; the climb from the western side of the Nepean River at Menangle up to Mittagong is sustained, a fact, hard to appreciate at high speed on the modern freeway. The highway climbs non-stop over a distance of 16 kilometres from the Pheasants Nest bridge over the Nepean River to Yerrinbool, before dropping before the final climb to reach the tablelands at Aylmerton, a climb of over 430 metres in 25 kilometres. Governor Lachlan Macquarie ordered the construction of a road, which became known as the Great South Road in 1819 from Picton to the Goulburn Plains and he travelled to Goulburn in 1820, but it is unlikely that a primitive road was finished at that time; the Great South Road was rebuilt and re-routed between Yanderra and Goulburn by Surveyor-General Thomas Mitchell in 1833.
The Main Roads Management Act of June 1858 declared the Great Southern Road, from near Sydney through Goulburn and Gundagai to Albury, as one of the three main roads in the colony. However, its southern reaches were described as only a'scarcely formed bullock track' as late as 1858; the road was improved in the mid-1860s with some sections near Gundagai "metalled" and all creeks bridged between Adelong Creek and Albury. Mitchell's route, except for the bypasses at Mittagong and Marulan is still followed by the current highway. Mitchell intended to straighten the route north of Yanderra, but was not granted funding, although his proposed route through Pheasants Nest has similarities to the freeway route opened in 1980. Mitchell's work on the Great South Road is best preserved at Towrang Creek, where his stone arch culvert still stands, although it was superseded in 1965 by a concrete box culvert which in turn was superseded by the current ro
The Andromeda Galaxy known as Messier 31, M31, or NGC 224, is a spiral galaxy 780 kiloparsecs from Earth, the nearest major galaxy to the Milky Way. Its name stems from the area of the Earth's sky; the virial mass of the Andromeda Galaxy is of the same order of magnitude as that of the Milky Way, at a trillion solar masses. The mass of either galaxy is difficult to estimate with any accuracy, but it was long thought that the Andromeda Galaxy is more massive than the Milky Way by a margin of some 25% to 50%; this has been called into question by a 2018 study which cited a lower estimate on the mass of the Andromeda Galaxy, combined with preliminary reports on a 2019 study estimating a higher mass of the Milky Way. The Andromeda Galaxy has a diameter of about 220,000 light-years, making it the largest member of the Local Group at least in terms of extension, if not mass; the number of stars contained in the Andromeda Galaxy is estimated at one trillion, or twice the number estimated for the Milky Way.
The Milky Way and Andromeda galaxies are expected to collide in ~4.5 billion years, merging to form a giant elliptical galaxy or a large disc galaxy. With an apparent magnitude of 3.4, the Andromeda Galaxy is among the brightest of the Messier objects making it visible to the naked eye from Earth on moonless nights when viewed from areas with moderate light pollution. Around the year 964, the Persian astronomer Abd al-Rahman al-Sufi described the Andromeda Galaxy, in his Book of Fixed Stars as a "nebulous smear". Star charts of that period labeled it as the Little Cloud. In 1612, the German astronomer Simon Marius gave an early description of the Andromeda Galaxy based on telescopic observations; the German philosopher Immanuel Kant in 1755 in his work Universal Natural History and Theory of the Heavens conjectured that the blurry spot was an island universe. In 1764, Charles Messier cataloged Andromeda as object M31 and incorrectly credited Marius as the discoverer despite it being visible to the naked eye.
In 1785, the astronomer William Herschel noted a faint reddish hue in the core region of Andromeda. He believed Andromeda to be the nearest of all the "great nebulae", based on the color and magnitude of the nebula, he incorrectly guessed that it is no more than 2,000 times the distance of Sirius. In 1850, William Parsons, 3rd Earl of Rosse and made the first drawing of Andromeda's spiral structure. In 1864, William Huggins noted; the spectra of Andromeda displays a continuum of frequencies, superimposed with dark absorption lines that help identify the chemical composition of an object. Andromeda's spectrum is similar to the spectra of individual stars, from this, it was deduced that Andromeda has a stellar nature. In 1885, a supernova was seen in the first and so far only one observed in that galaxy. At the time Andromeda was considered to be a nearby object, so the cause was thought to be a much less luminous and unrelated event called a nova, was named accordingly. In 1887, Isaac Roberts took the first photographs of Andromeda, still thought to be a nebula within our galaxy.
Roberts mistook Andromeda and similar spiral nebulae as solar systems being formed. In 1912, Vesto Slipher used spectroscopy to measure the radial velocity of Andromeda with respect to our Solar System—the largest velocity yet measured, at 300 kilometres per second. In 1917, Heber Curtis observed a nova within Andromeda. Searching the photographic record, 11 more novae were discovered. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred elsewhere in the sky; as a result, he was able to come up with a distance estimate of 500,000 light-years. He became a proponent of the so-called "island universes" hypothesis, which held that spiral nebulae were independent galaxies. In 1920, the Great Debate between Harlow Shapley and Curtis took place concerning the nature of the Milky Way, spiral nebulae, the dimensions of the Universe. To support his claim of the Great Andromeda Nebula being, in fact, an external galaxy, Curtis noted the appearance of dark lanes within Andromeda which resembled the dust clouds in our own galaxy, as well as historical observations of Andromeda Galaxy's significant Doppler shift.
In 1922 Ernst Öpik presented a method to estimate the distance of Andromeda using the measured velocities of its stars. His result placed the Andromeda Nebula far outside our galaxy at a distance of about 450,000 parsecs. Edwin Hubble settled the debate in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of Andromeda; these were made using the 2.5-metre Hooker telescope, they enabled the distance of Great Andromeda Nebula to be determined. His measurement demonstrated conclusively that this feature was not a cluster of stars and gas within our own galaxy, but an separate galaxy located a significant distance from the Milky Way. In 1943, Walter Baade was the first person to resolve stars in the central region of the Andromeda Galaxy. Baade identified two distinct populations of stars based on their metallicity, naming the young, high-velocity stars in the disk Type I and the older, red stars in the bulge Type II; this nomenclature was subsequently adopted for stars within the Milky Way, elsewhere.
Baade discovered that there were two types of Cepheid variables, which resulted in a doubling of the distance estimate to Andromeda, as well as the remainder o
M31 HEAT rifle grenade
The M31 HEAT is a fin-stabilized anti-tank rifle grenade designed in the late 1950s to replace the Belgian ENERGA rifle grenade, adopted by the US Army and US Marines as an emergency stop-gap measure during the Korean War. Like the ENERGA, it has a nose-initiated, based-detonated HEAT warhead, but unlike the ENERGA, the mechanical impact fuse system is replaced with a less complex and more reliable piezo-electric fuse system which allows higher angles of impact, up to 65 degrees. On impact, the nose cover collapses, crushing a crystal-like material, which sends an electric current through a separate wire to the warhead's detonator, located in the base of the warhead. A mechanical safety, comprising a set back system located in the warhead's base, grounds the firing circuit and prevents the accidental explosion of the warhead. On firing, the sudden launch acceleration causes the set-back's three disks to rotate 90 degrees, each in succession to the other, with the rotation of the third disk removing the grounding after 10 meters of flight and completing a firing circuit for the current to flow from the nose to the detonator in the base.
Compared to the ENERGA, the M31 is lighter in weight and has a smaller-diameter warhead—i.e. 75mm vs 66mm. Penetration for the M31 is estimated to be 200 mm / 8 inches for steel armor plating and twice that estimate for concrete; the warhead technology developed for the M31 was used for the future M72 LAW antitank rocket. The M31 was designed to be fired only from the M1 Garand, but could be fired from both the M14 and M16 rifles. To launch the M31, a detachable spigot-type grenade launcher is fitted to the muzzle of the rifle. A M3 ballistic cartridge is loaded into the rifle's chamber; the hollow tail unit of the rifle grenade is fitted over the grenade launcher. Official military manuals recommend that the M31 HEAT be fired from either the standing or kneeling position and that it is only accurate against armored vehicles if fired at close ranges. While claimed to be effective against main battle tanks and armored vehicles when first introduced, in 1972 the US Army stated in its revised anti-armor warfare manual that the M31 HEAT was only effective against light tanks and thin-skinned vehicles.
Various US military manuals issued in 1972 still had sections on the M31, but by the end of the Vietnam War, both the US Army and US Marines had phased out muzzle-launched rifle grenades, in favor of the M72 LAW disposable rocket in the anti-armor role and the M203 under-barrel grenade launcher in the squad fire-support role. In the 1977 revision of US military anti-armor warfare manuals, the M31 HEAT was no longer listed. FM 23-3 Tactics and Concept of Antiarmor Warfare, published US Army August 1972 Jane's Infantry Weapon's System 1976, page 452, Watts Publishing ISBN 0-531-03255-8 US Rifle Grenades, WW2 And After - inert-ord.net