M-65 (T-131) Atomic Gun gallery

(Mack T-8 image). After building the gun, the task of manufacturing its transporter had to be undertaken, and for this, two former double ender concept tank transporters of 1945 were used. Two prototypes developed by Mack called T-8E and T-8E1 were completed in 1945, but the programm was canceled due to the end of WWII. The T-8 transporter had two units, (front and rear), both powered, with the the rear unit being detachable to load the vehicle on the loading platform. The truck weighed 43.03 tons, was over 18 meters long, could carry up to a 36.25 tons load, and was powered by two Hall-Scott 44I engines of 240 hp each.
(Mack T-9 image). Faced with the new need, the Mack T-8E1 prototype was prepared and modified to be able to transport the T-131 cannon, and thus in 1950 the new Heavy Transporter T-9 was presented. The new truck measured 21.58 meters in length and was powered by two Ford GAA V8 tank engines of 500 hp each, which allowed it a top speed of 51 km/h. Unfortunately, despite being a very capable vehicle, after a period of testing it was decided that the selected vehicle would be the other contender, the Kenworth T-10 Heavy Artillery Transporter.
(Kenworth T-10 image). Kenworth was the other competitor to build the new Heavy Transporter and presented a prototype designated as the T-10 Heavy Artillery Transporter. This vehicle was composed by a front vehicle called “A unit” and a rear vehicle called “B unit”. Kenworth only manufactured one prototype and after winning the competition designated the series vehicles as “4×4 Heavy Gun-Lifting Front Truck M-249 (T-10A)” for the tractor and as “4×4 Heavy Gun-Lifting Rear Truck M-250 (T-10B)” for the rear unit.
The 280mm T-131 Gun designation remained until 1960, when it was changed to the better known “280mm Heavy Motorized Gun M-65“. This system was classified as a heavy mobile long-range artillery system and consisted of the 280mm rifled barrel (M66) and the Gun carriage M30 (T-72). The gun had a separate double recoiling system with a primary recoiling mass that operated on the barrel and the cradle, and a secondary recoiling mass that operated between the top and bottom carriage. The primary element controlled the recoil of the barrel while the secondary element returned the weapon to in-battery position.
The gun fired from a fixed mount and was designed to attack fortifications, targets of high strategic value, communication centers and to carry out counter-battery fire against enemy artillery. It had two types of ammunition, the HE T-122 conventional shell and the T-124 Atomic Projectile with the W-9 warhead. The T-124 was replaced in the mid-1950s by the T-315 carrying the W-19 “Katie” atomic warhead. The conventional ammunition had a range of 28.70 km while the nuclear T-124 had a maximum range of only 24.75 km due to its high weight and poor aerodynamics. The nuclear T-315 was lighter and reached 30.70 km. There was also a practice shell designed as T-299.
The barrel had a cylindrical breechblock that closed vertically and was manually operated. The ammunition was separated loaded and the barrel had to be at an elevation angle of 11º to be loaded. The primary recoil system was of the hydropneumatic type and consisted of two recoil cylinders and a recuperator cylinder and was mounted in the cradle under the barrel. A secondary recoil system was also of the hydropneumatic type and consisted of a recoil cylinder and a recuperator cylinder attached to the firing base and connected to the upper part of the gun carriage. The barrel had an external hydraulic system that was in charge of raising the barrel and ramming the shell. If necessary, these functions can be performed manually.
The Gun Carriage T-72 consisted of 3 main elements that were the top carriage, the firing base and the float pan. The top carriage supported the barrel and various operational elements of the piece, while the firing base and the float pan formed the bottom of the carriage that was in contact with the ground. The float pan was a kind of platform located at the rear end of the carriage that allowed the barrel to be manually traversed 7.5º to each side, although the barrel could be fully rotated by lifting the float pan off the ground and rotating the barrel on the firing base. The gun could fire at an elevation angle between 0º and 55º.
The gun had two positions, the travel position, in which it was retracted on the carriage, and the firing position in which the barrel protruded from the carriage. To move the barrel, the M-249 (T-10A) front truck had a 27.2 tons capacity power winch to pull it to the firing position. When it had finished its mission, the same truck used the power winch to pull the breechblock and put the barrel back in the travel position. The gun (without carriage) weighed 19,049 kg and measured 13.02 meters in length.
Another fundamental part of the M-65 Atomic Gun (as it was popularly known), was the T-10 transporter. The front truck designated as M-249 (T-10A) had two axles and 4×4 configuration, carried a hydraulic steering and air brakes. It was powered by a 375 hp 6-cylinder Continental AO 895-4 air cooled gasoline engine coupled to an Allison TX-500 manual transmission with three forward gears and one reverse gear. The brakes on both trucks were interconnected and could be operated by the front truck driver. In addition, both drivers had an interphone to communicate while transporting the gun. The driver in charge of the maneuvers was that of the M-249 front truck, who reported at all times to the rear driver. The truck had a hydraulic system to manage the loading platform and the motor winch.
The rear truck is designated as M-250 (T-10B) and also had two axles and 4×4 layout. This truck had the same engine as the M-249 front truck, but the driver does not have a gearbox, he can only provide more braking to his vehicle if necessary, but he could not reduce the braking of the front truck M-249 or the whole M-65 Gun system. It also had an engine rev limiter so that the engine in the rear truck had no more revs than the one in the front truck. This truck also had a hydraulic pump for handling the loading platform. The M-250 rear truck performed the same function as those used in some large American tiller ladder fire trucks, facilitating turning and improving maneuverability.
Apparently, the official motive for designing nuclear shells was to ensure the ability to carry out high precision all-weather strikes, because the aircraft of the 1950s could not guarantee them. However, the unofficial reason was that Navy and Army had much more experience with artillery and were more comfortable than with ballistic missiles. Over time, missiles improved their capabilities and the use of these nuclear shells became increasingly difficult, since currently the possibility of a WWII-type war is almost impossible and their use in urban centers in today’s Asymmetric wars would not be morally acceptable to anyone.
Around 21,000 people from the American Department of Defense participated in the preparation of this exercise. Two T-131 guns were deployed for the exercise in Nevada along with a detachment of 2,600 soldiers and 700 observers. On May 25, 1953 the No.9 T-131 Atomic Gun fired a T-124 nuclear projectile at Frenchmans Flat in the Nevada nuclear testing grounds. This event was called “Shot Grable” and it was the 10th test within the Upshot-Knothole tests, in which 11 nuclear tests were carried out. This was the only time in history that a gun has fired a nuclear projectile.
During the “Shot Grable” exercise the T-124 nuclear shell carried the W-9 warhead charged with 50 kg of highly enriched uranium and was fired 7 miles (11.5 km) away. The shell exploded at a height of 159.29 meters (524 feet) and produced a yield of 15 kilotons, or a detonation equal to 15,000,000 kg of TNT. Ballistic calculations for this test had been performed at the Fort Sill, Oklahoma range with conventional HE shells. Shooting tests at this firing range were limited to 7 miles, hence the range of the “Shot Grable” shot.
After the nuclear detonation, the 2,600 soldiers had to attack two targets located 2.4 and 2.8 km southeast of ground zero …… !!!. Fortunately for them, winds and dust almost totally prevented the attack. However, despite the inconvenience, some troops managed to approach only 700 meters to the south of the explosion. Nowadays, it seems incredible to us that those soldiers were ordered to stand so close to a place where only a few minutes ago there had been a nuclear explosion, but those were other times, and the heat of the Cold War led both sides to carry out these kinds of dangerous follies.
The guns were deployed mainly in Germany within the USAREUR (United States Army and EURope), attached to the 7th U.S. It was formed from 5 Field Artillery Battalions (FAB) hosted in the 42nd Field Artillery Group that were distributed in different parts of Germany. On paper, each Battalion consisted of 3 firing batteries with two guns each, that is, 6 guns in each Battalion. Each firing battery had its own fire control and surveillance detachment and could operate independently for two weeks if necessary. The first 5 Battalions deployed to Germany in 1953-54 were the 59th. 264th, 265th, 858th and 867th FAB, originally formed at Fort Sill, Oklahoma and Fort Bragg, North Carolina in 1952. These Battalions were mainly in the service of an Army or an Army Corps to support the front line infantry or to protect important facilities.
Each Battalion consisted of 494 men and each battery consisted of 101 men, two 280mm guns, four 5-ton trucks with ammunition, 1 electric generator, and several support vehicles. Each gun took between 12 and 15 minutes to occupy the firing position and about 10 minutes to leave the position after firing. In a real situation, the guns were positioned between 8 and 12 km apart and moved frequently to avoid enemy counter-battery fire. Typically, guns were attempted to be positioned at night or in poor visibility to increase their protection.
This was the only American gun that could full circle traverse without displacement, which was very useful for attacking targets on the sides or even behind the piece. The T-124 and T-315 nuclear shells weighed 364 and 272 kg respectively and had the destructive capacity of the Hiroshima bomb. This destructive capacity was highly appreciated within the US Army and it was believed that it would have been very useful to stop a possible invasion of Europe by the Soviets. In 1957, the Soviets deployed two gigantic artillery pieces capable of firing nuclear shells, they were the 2A3 Kondensator and the 2B1 Oka-Transformator.
The M-65 guns were not only used to fire nuclear shells, but were used as powerful pieces of heavy artillery. Exercises to keep the crews well trained were frequent and during these occasions the difficulty of moving these gigantic guns was evident. It had been ruled that sharp bends should not be negotiated at more than 8-9 km/h and open curves at more than 16-17 km/h. You also had to be extremely careful when driving through banked curves because of the danger of the vehicle rolling over, so the speed was also limited to about 15 km/h. However, the cruising speed on the highway was stipulated at around 40 km/h.
Only 20 M-65 guns were built, however the number of heavy transporters reached 33 complete units. This weapon system was exceptionally expensive at about $ 800,000 a unit and also the useful life of the barrels was only about 300 shots. A curious fact is that the breech and carriage used to be labeled what both items cost as a way to remind the crews how valuable they were in their hands. For example, the tube cost 116,722 dollars and the carriage 266,845 dollars, but despite this warning, it is known that there were accidents such as one gun that ran off the road and ended in a lake during a night exercise in Grafenwohr.
Later the Battalions that used the M-65 were changing, so in 1957 it was the 216th, 264th, 265th, 613th, 867th and 868th Artillery Battalions of the 42nd Artillery Group who had them. Lastly, in 1961 the atomic cannons were included in the artillery battalions 2nd/38th Artillery Group (ex-216th), 3rd/39th Artillery Group (ex-867th) and 3rd/82nd Artillery Group (ex-264th). Finally, in 1963 all the M-65 guns were retired when new 155 and 203mm nuclear projectiles with similar or greater range and same yield came into service. This new rounds could be fired by self-propelled pieces that offered infinitely superior mobile capabilities. In addition, the logistical support and the cost of these SPH were much lower, so it did not make sense to operate with the famous M-65 atomic cannons.
From the twenty M-65 Atomic Guns, 3 complete guns (with their transporters) are preserved, which can be seen at the U.S. Army Ordnance Museum,(Aberdeen, Maryland), the U.S. Army Artillery Museum, (Fort Sill, Oklahoma) and the National Museum of Nuclear Science & History, (Albuquerque, New Mexico). There are four more cannons preserved in different condition exhibited in as many places, but they lack their heavy transporters.
The famous M-65 nicknamed “Atomic Annie” is preserved in Fort Sill, Oklahoma. This is the original and unique cannon that actually fired a nuclear shell during the “Shot Grable” exercise. Although in most publications the 280mm M-65 gun is generically named as “M-65 Atomic Annie“, this definition is wrong except for this one piece.
It is possible that this cannon is now seen as a dinosaur that only served to spend huge amounts of money on something that was not even moderately effective, who knows. But we must not forget that at the time it served to provide the infantry with a powerful and accuracy weapon capable of stopping in its tracks a mass attack against Europe by the Warsaw Pact, and also …, to smash all crystals of the barracks and surroundings in one go during demonstrations!!

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