T - 54 / 55 Fire Controls The T - 54 and T - 55 combines a high - velocity gun with a highly mobile chassis , low silhouette , and exceptional long - range endurance . The T - 54 / 55 tanks have been produced in greater quantity than any other tank in the world . Seven main production models have been widely used throughout the Warsaw Pact and in many other countries . The T - 54 / 55 series has been manufactured in Czechoslovakia and Poland as well as in China where it is known as Type 59 . More than a dozen countries have produced upgraded T - 55 variants with similar capabilities in protection and lethality . The tank featured many innovations , many of these being in the fire controls of the T - 54 and the T - 55 . The Commander . The commander sits directly behind the gunner under a 360 degree traversable commander ' s cupola . Five wide prism vision blocks give a good view and all - round orientation . For sighting and quick target designation a binocular observation device is inserted in the center . In the first model was the TPK - 1 . It has a x2 . 75 magnification and also accommodates one of the five vision blocks . Not long after becoming mass - produced , all TPK - 1 devices were replaced by TPKU - 2B devices . This device did not have a vision block of its own ( reducing the total number to 4 ) , yet it gave a x5 magnification . A distance measuring scale was added on the lenses , it could reveal the approximate distance of a 2 . 7 meter tall target ( an average NATO tank ) at ranges up to 3000 meters . In case of the damage of the prism mirror , the device could be opened , the prism pulled out and replaced . Together with the possibility to traverse the turret , the commander could also seek for targets independently from the gunner . With a push of a button located on the left handle of the TPKU - 2b device , the turret swung into the center of the commander ' s TPKU - 2b visor lines not only in horizontal plane , but in vertical too . The turret swung with maximum recommended speed on the view line of the commander and stopped with correspondence of the visor lines . However , the commander had to hold on to his dome and work against the turret rotation , keeping the target in his sights until the turret stopped . This designation method was not totally accurate , but accurate enough for the gunner to see the target in his field of vision . For operations during night time , the observation devices could be disconnected and replaced by an active infrared night vision device of the TKN - 1 type or similar . The infra - red searchlight attached to the commander ' s dome had to be coupled to the night vision device with bolts and electric wires leading inside the tank . For this one of the four vision blocks had to be removed , creating a gap to pull the wires through . However , the infra - red floodlight could effectively illuminate only at distances up to 400 meters with a x2 . 75 magnification . Though the much larger gunner ' s infra - red floodlight helped to see effectively up to 800 meters , but only at the frontal arch of the turret . Such early night vision devices had many drawbacks , and the TKN - 1 was no exception . The bright infra - red floodlights could be easily spotted by modern passive infra - red night vision devices and thermal sights at ranges exceeding the visibility of the active infra - red devices like the TKN - 1 . Moreover , the eyepieces of the TKN - 1 lay very close to the body of the TPKU - 2B what made the commander ' s rubber frontal headrest an obstacle , without which keeping the eyes on the eyepieces during movement of the vehicle very difficult . The gunner . The gunner sits in the lower front of the commander . He uses a telescopic day sight as his main sight . In the T - 55A this was the TSh2B - 32P ( in its final version ) , an advancement of the sight telescope of T - 34 . When not engaging targets , the gunner can use his telescope to scan the horizont , or use his own prism vision block for a much wider frontal view . For shooting at night the gunner used his TPN - 1 telescope , which replaced the prism vision block from the T - 54B onward . Under the day sight is the gunner ' s control pad with which he controls the turret and fires his weapons - right button for the main gun , left button for the machine gun . The turret is operated electrically , but can also be traversed , aimed and fired mechanically , though overall combat efficiency severely suffers . The T - 54 and T - 55 tanks received full gun stabilisation in 1956 with the STP - 2 Tsyklon stabiliser system ( from D - 10 tank gun ) . The STP - 2 stabilised the main gun in both horizontal and vertical planes . However the lack of a ballistic computer still remained an issue . The tank was not accurate firing if moving left or right respectivelly to the target , because even though the gun was stabilised , it couldn ' t keep a lock on the target , the shell fired from such a platform would keep on moving sideways as fast as the tank moved sideways off the target . For example , if the T - 54 / 55 was moving at 40 km / h speed with the stabilised gun aimed at the target at a 1000 meter range , moving sideways ( the hull facing the target with its side ) , the shell fired by the T - 54 / 55 would fly aproximetly 1 . 5 meters off to the side from the point of aiming . Same drawback also applies for vertical movement . If the T - 54 / 55 was moving down hill at considerable speed , with the gun aimed at the target , the fired shell would fall lower than the point it was aimed at . The gunner had to be careful to figure out where to aim the stabilised gun around the target to avoid such overshooting . That ' s one of the particular reasons why a well - trained gunner was a very useful asset in a T - 54 and T - 55 tank . Nevertheless , the tank could fire accurately despite the lack of ballistic computers if the tank was moving at lower speed , or if heading straight towards its target . Also , additional markings to either sides of the main aiming chevron on the TSh2B - 32 sight could help the gunner to aim more precisely on the move . Main weapons . The D - 10 is a 100mm high - velocity gun , with a 53 . 5 caliber length barrel . Its high muzzle velocity ( 895 m / s ) gave it good armor penetration performance by late World War II standards . It was originally designed to equip the SU - 100 tank destroyer with this gun ( the D - 10S ) , but after world war II was mounted on the T - 54 main battle tank as the D - 10T ( for tankovaya , ' tank ' adj . ) . From world war II era , up to the 1960s , there were a few types of tank rounds offered for the D - 10 gun both of the T - 54 / 55 and SU - 100 ( before it was phased out of service ) . These were the UOF - 412 15 . 6 kg high - explosive fragmentation with a 1 . 46 kg TNT warhead . The 100mm OF - 412 HE fragmentation warhead was 60 % heavier in both total weight and bursting charge than the equivalent 88mm tank guns found on German Tiger tanks . Antitank ammunition available from World War II until the late 1960s was based on the UBR - 412 round : the BR - 412 APHE projectile , with the BR - 412D and BR - 412B ammunition becoming available shortly after world war II . The BR - 412 APHE round could penetrate 150mm of steel armour at a distance of 1000 meters . Due to the increase of armour protection on tanks in post world war II era , the T - 54 / 55 was forced to rely on HEAT ( shaped - charge ) ammunition to engage tanks well into the 1960s before more modern kinetic energy rounds were developed , despite the relative inaccuracy of this ammunition at long ranges . The shortage of HEAT rounds in all soviet tanks during world war II was solved not long afterwards once the soviet industry passed the devastation of the war . High - explosive anti - tank rounds included the 3UBK4 with 3BK5M warhead ( which could penetrate 380mm of steel armour ) , later replaced by the 3UBK9 with 3BK17M warhead . These rounds were the main HEAT munitions the T - 54 / 55 received until the developments of barrel - launched 100mm guided missiles in the 1980s . The gunner ' s sight was modified over and over again and adapted to new kinds of ammunition . At first there were scales for the HEF shells ( OF - 412 ) with full and with reduced powder charge , for the APHE shell ( BR - 412 ) and for the coaxial machine gun . In 1964 , soviet designers started to work on an improved 3UBM6 hyper - velocity armour - piercing discarding sabot round ( as opposed to APHE rounds the D - 10 used before ) . In 1967 , the 3BM6 HVAPDS round entered service . It was soon replaced by the 3BM8 projectile in 1968 , with a tungsten carbide penetrator , giving it a 318mm penetration against steel armour at point - blank range . The SABOT rounds were very effective due to their accuracy and high - velocity which gave the rounds a very flat flight trajectory . The tank gunners in the soviet army were taught that they can hit a tank - sized target without having to input the range into the scales if firing a SABOT round with the target being at or on the outskirts of 1000 meter ranges . The effectiveness of this point - and - shoot method brought the combat efficiency of the T - 54 / 55 a step closer to more modern tanks such as the Leopard 1 and T - 64 . New scales were constantly added to the TSh2B - 32 sight allowing range input for new types of ammunition . A dial to the left side of the gunner ' s eyepiece served for selecting of the x3 . 5 times to x7 times zoom . The gunner could turn on the sight illumination during night time , which made the distance and aiming markings become visible in red against the dark background of the night . For accurate shooting during the night the gunner could use his TPN - 1 device working on the active infrared principle . It is an electro - optical monocular telescope with a x5 . 5 times zoom and 6 degree field of view . Its effective range of illumination is 600 – 800 meters . When firing the main gun , an automatic screen is closed for a short time . Otherwise , observation with the TPN would be impossible due to the bright flash . In addition , the light from the muzzle flash can burn out the emitter layer of the picture converter which will make the TPN useless . The TPN is connected with the stabilized parts of the main gun . Therefore accurate aiming on the move during the night is possible as well . A big floodlight ( the L2AG , the so - called Luna floodlight ) is placed on the right side of the turret , with an elbow fastened to the stabilised main gun and serves for the purpose field lighting . With this fixture the floodlight always follows the movement of the cannon , yet has to be calibrated to shine into the center chevrons of the TPN sight . For this some periodic crew work is required . The shooting with the TPN was relatively easy . There was the main triangular chevron in the center of the reticle . Its upper tip represented where the BR - 412 APHE would land at a 700 meter range , and where the machine gun rounds would land at 500 meter range . Many variants of the TPN - 1 were adopted for the T - 64 , T - 72 and even T - 80 tanks with improved active and possible passive night vision .