The U-5TS (production designation 2A20) tank gun is a 115 mm-calibre weapon that was fitted almost exclusively to the Soviet Union's T-62 main battle tank. It was the first smoothbore weapon designed for tanks, and heralded the change in main armament from rifled cannons.
History As the T-54/55 series began to replace the T-34 tanks in the Soviet Army in the 1950s it was recognised that the standard NATO tanks of the time—the Centurion and M48 Patton—had armour that could not easily be defeated by the existing ammunition for the 100 mm D10 gun that the new tanks carried. The Soviets set about designing a new "heavy" vehicle which was required to complement the tanks in an overwatch capacity and to provide greater anti-armour capability.
The new vehicle, the T-62, was to be equipped with a new smoothbore design—which allows higher velocity and greater armour penetration with kinetic rounds—based on an enlargement of the 100 mm 2A19 anti-tank gun that had entered production in 1955. The new weapon, designated as U-5T, could penetrate 300mm of vertical RHA at 1,000 metres and re-established a comfortable penetration capacity against Western armour.
Though the T-62 would have variable success in the conflicts it was involved in, the U-5TS would remain a formidable weapon that proved capable of penetrating the armour of any comparable NATO tank until the deployment of third generation MBTs in the late 1970s and early 80s. This was proven by examination of Iranian Chieftain and M60s knocked out by Iraqi T-62s during the Iran–Iraq War. These examinations led to the development of add-on armour packages such as Stillbrew to try to counter the U-5TS.
Ammunition Another first with this gun was the use of armour-piercing fin-stabilized discarding-sabot ammunition, with the initial 3VBM-1 rounds featuring steel penetrators. The subsequent development of this type of ammunition for this gun led to an array of penetrator designs and different materials with the final model, the 3UBM-13, using depleted uranium. In accordance with later Soviet and current Russian practice an anti-tank guided missile, the 9K118 Sheksna, has been developed for use with the T-62 and U-5TS. There is also HE-FRAG and HEAT ammunition available for this weapon.
Due to the comparatively low height of the T-62 design - in line with Soviet tank design philosophies of the time - the U-5TS is limited to a rate-of-fire of 6-10 shots per minute due to little room for the loader to perform his activity. Experienced loaders were capable of reloading the gun in 6 seconds.
DesignationOriginDesigner & producerYearSub-projectile lengthPenetrator dimensionL/D ratio (sub-projectile / penetrator only)Penetrator material & weightSub-projectile weight with sabot / Projectile WeightPropellant type & weightChamber pressureMuzzle velocity Velocity dropPerforation at normal and oblique incidencesNotes3BM-3OAO Zavod1963⌀ 42-30 × 436 mm 12.5:1 (avg. diameter to penetrator length)Steel Rod5.5 kg / 4.0 kg 1615 m/s128.5 m/s (at 1000 m)270 mm at 0° at 2000 m, 100 mm at 60° at 2000 m Has Tungsten Carbide Tip3BM-4OAO Zavod1963⌀ 42-30 × 436 mm 12.5:1 (avg. diameter to penetrator length)Steel Rod5.5 kg / ??? kg 1650 m/s128.5 m/s (at 1000 m)220 mm at 0° at 2000 m, 110 mm at 60° at 2000 m Does not have the tungsten carbide tip3BM-6OAO Zavod1967⌀ 42-30 × 436 mm 12.5:1 (avg. diameter to penetrator length)Steel Rod5.34 kg / 3.86 kg 1680 m/s128.5 m/s (at 1000 m)240 mm at 0° at 2000 m, 120 mm at 60° at 2000 m Estimated with Lanz Odermatt Formula at 60 degrees and vertical performance being based on 3BM-4 since both have a piercing cap.Does not have Tungsten Carbide Tip3BM-21OAO Zavod1975Steel Rod6.26 kg / ??? kg 1600 m/s128.5 m/s (at 1000 m)330 mm at 0° at 2000 m, 135 mm at 60° at 2000 m Features Tungsten Carbide Tip with a Tungsten Alloy Piercing Cap3BM-28OAO Zavod1978⌀ 30mm avg. × 326 mm 10.8:1 (avg. diameter to penetrator length)Depleted Uranium Rod4.91 kg / ??? kg 1650 m/s95 m/s (at 1000 m)350 mm at 0° at 2000 m, 205 mm at 60° at 2000 m Estimated with Lanz Odermatt Formula at 60 degrees and these as reference. Russian rocket 115 mm U-5TSThe Penetrator was later re-used to make the 125mm 3BM-29 APFSDS. Penetrator Weight = 4.36 kg3BM-36OAO Zavod1988⌀ 28mm avg. × 380 mm 13.5:1 (avg. diameter to penetrator length)Depleted Uranium Rod??? kg / ??? kg 1650 m/s80 m/s (at 1000 m)385 mm at 0° at 2000 m, 225 mm at 60° at 2000 m Estimated with Lanz Odermatt Formula against 260BHN SteelThe Penetrator from 3BM-32 Vant was re-used to make the 3BM-36. Penetrator Weight = 4.3 kgBD/36-2Royal OrdnanceHeavy Tungsten Alloy Rod5.93 kg / 3.59 kg 1600 m/s55 m/s (at 1000 m)385 mm at 0° at 2000 m, 225 mm at 60° at 2000 m Ammunition specs it's roughly equivalent to 470mm LOS at 60 degreesThe 115 mm BD/36-2 APFSDS-T round has a tungsten-nickel-iron penetrator derived from the design of the British 105 mm H6/62 APFSDS-T. Made for Egyptian Production.M1150Mecar(subsidiary of Nexter Systems)Heavy Tungsten Alloy Rod6.5 kg / ??? kg 1635 m/s>500 mm LOS at 60° at 2000 m3BM-21M⌀ 22 × 640 mm 26:1Heavy Tungsten Alloy Rod???kg / ???kg 1610 m/s 65 m/s (at 1000 m)490-495 mm at 0° at 2000 m, 285-290 mm at 60° at 2000 m Assuming its Lekalo Rod with 50m/s less muzzle velocityNew 115mm in Development.Group of youngsters listening to an old man Appears as a 3BM-60 Svinets-2 penetrator inside a 115mm projectile. Rocket drawing
Current and former users
Lebanese Christian Militia
See also Weapons of comparable role, performance and era Royal Ordnance L11A5: British 120-mm rifled equivalent
Notes and references
Zaloga, Steven; Modern Soviet Combat Tanks; Osprey Publishing, London; 1984
External links
Das Panzerdetail - die Munition der 115 mm Kanone U-5TS / 2A20 / 2A21 / D-68