PKT (PKMT) Machine Gun

After its acceptance into service in 1961, the PKT (GRAU index 6P7) was used as the standard machine gun for enclosed Soviet armoured fighting vehicles beginning in 1962. The PKT weighs 10.5 kg. It a heavier than a PK which weighs 9.0 kg, despite having no stock or pistol grip. The first and most obvious visual differences that distinguish the PKT from the basic PK are the absence of a buttstock, pistol grip, trigger, bipod mount and sights. These modifications reduced the degree of parts commonality between the PKT from its parent design, but were generally beneficial adaptations to optimize the weapon for its role.

When linked to an electric firing system, the machine gun can be fired either by depressing the trigger button on the gunner's control handles or by pressing the manual trigger button located on the trigger unit installed at the back the receiver of the machine gun. The latter method may be necessary if the tank loses electrical power or if some other issue makes it impossible to fire the machine gun normally.

For the purposes of a tank coaxial machine gun, the design of the PKT and PKMT can be considered exemplary as it is unusually short and compact compared to its direct foreign counterparts. This is due to its two-stage feeding mechanism, where fresh cartridges are pulled out of the belt links and then loaded into the chamber by the bolt assembly rather than pushed through the links and into the chamber in a single motion when feeding. In connection with this feature, the Kalashnikov design team placed the belt feed tray directly above the chamber of the barrel. This greatly shortened the total length of the receiver compared to machine guns like the FN MAG, which needed to have its feed tray located far behind the chamber of the barrel for its single-stage push-through feed mechanism to work, resulting in its receiver becoming very long. 

Officially, the nominal maximum range of the PKT(M) is 4,000 meters, and its maximum sighted range is 1,300-2,000 meters on Soviet armoured fighting vehicles. The exact sighting range depends on each vehicle and is predominantly influenced by the capabilities of their sights and fire control system. When firing ball ammunition, the point-blank range for a standing man of average height (170 cm) is 700 meters. The point-blank range against a torso-sized target (height of 50 cm) is 440 meters, and the point-blank range against a running man (height of 150 cm) is 670 meters. The maximum effective range against ground targets is stated to be 1,000 meters, because this is the tracer burnout range. The range of accurate fire is 800 meters. Aimed fire on point targets out to 1,000 meters is feasible when firing the PKT with the high magnification sight of a tank. For infantry machine guns relying on iron sights, there is a possibility of the gunner mistaking tracer burnout with tracer strike on the ground, making fire correction more difficult. 

In terms of firing precision, the performance of the machine gun may vary depending on the mount upon which it is fitted. When installed on the various fixed mounts used in Soviet armoured vehicles, mainly coaxial mounts, the dispersion of the PKT(M) is considered normal if 8 rounds from a 10-round burst (80%) fit within a 14 x 16 cm rectangle at 100 meters. Machine guns that do not meet this standard are subject to an armoury-level teardown for corrective action, or replacement.

In 1969, the PKT was replaced by the PKMT (GRAU index 6P7M) created on the basis of the PKM machine gun. When the PKM replaced the PK on the production lines in 1969, the production of the original PKT also halted. The PKMT and the PKT differ in the same details where the PK and PKM models differ. The most noticeable change was the removal of the fluting on the barrel, giving the PKMT barrel a smooth external surface, but in other regards, the PKMT matches the infantry PKM in the receiver. Functionally, the PKT and PKMT are identical, and they are normally considered as such in use, even as far as having PKMTs being often referred to as PKTs.

One of the most important modifications of the PKT that distinguished it from the infantry versions was the new gas regulator mechanism. As in the infantry versions, the gas regulator is integral to the PKT barrel and not the gas tube. The same three-position adjustment functionality was retained, but the gas regulator of the PKT would not vent gasses outside the gas tube at all so that the accumulation of propellant gasses inside the armoured vehicle is minimized. On a PK or PKM, the gas regulator adjusts the amount of gas pressure acting upon the operating piston by changing the amount of gasses vented out of the regulator chamber depending on the selected position. Position "1" vented out gasses through two holes, position "2" restricted one of the two vent holes so that less gas was vented, and position "3" shut both vents so that no gasses were vented at all. On a PKT, the barrel has a narrower gas port to permit a reduced flow of gasses and the gas regulator further restricts the passage into the gas tube.

Position "1" is the default setting for a clean and well-lubricated weapon, and the next two settings are intended for situations where the machine gun begins to slow down for whatever reason, typically from an increase in friction from a buildup of propellant residue in the receiver. This is done by progressively increasing the amount of gasses that can flow into the gas tube to act upon the operating piston. Position "2" should be used after 3,000 rounds have been fired from the machine gun without cleaning, and position "3" should be used after another 3,000 rounds have been fired.

The gas regulator valve is adjusted between the three possible positions by turning the valve knob. The valve knob is knurled for this purpose. When the PKT(M) is installed in armoured vehicles, the gas regulator normally does not require adjustments during combat, but if necessary, the operator must use a special tool or wear insulated gloves as the valve knob will be extremely hot.

It was not possible to completely prevent all fumes from seeping out of the machine gun through various ports and openings simply because its open-bolt operating system leaves the mouth of the empty chamber open, but the PKT has an advantage over many other GPMGs because the ejection port is sealed by a spring-loaded flap until the moment of ejection. This can reduce the amount of fumes that exit the weapon by some amount.


The cyclic rate of fire of the PKT and PKMT is 700 to 800 RPM. The firing rate was deliberately increased from the 650 RPM rate of the PK and PKM because it was determined to be optimal for a mounted machine gun, where recoil control is a non-issue. For such a weapon, the deciding factor was that a large supply of ammunition could be carried aboard the armoured vehicle so a higher rate of fire provided a more rational compromise between a variety of requirements including ammunition conservation, hit probability on infantry targets, fire correction, barrel heating rate, and so on. This increased fire rate was paired with a thicker barrel.

In practice, the PKT(M) was specified to have an average fire rate of 250 rounds per minute. The bullets fall to a transonic speed at a range of around 700 meters and fully transition to subsonic flight at a range of around 850-860 meters. With the shift from supersonic flight to subsonic flight, the dispersion characteristics can suffer due to the shift in the center of pressure due to the change in the airflow characteristics. This is a characteristic of virtually all bullets designed for supersonic flight, and is a consequence of the aerodynamic design of such bullets being optimized for a supersonic flight regime. It is likely that since consistent dispersion performance is only guaranteed up to a nominal distance of around 860 meters, 800 meters is considered the effective range of the PKT(M) against point targets, taking into account the greater air density in very cold conditions. The maximum effective range against ground targets is considered to be 1,000 meters. Firing at ground targets from longer ranges is possible, albeit with reduced accuracy, so in general, only area targets should be engaged. Based on these metrics, the PKT has a slightly longer reach than its equivalents chambered in 7.62x51mm, to the order of 50-100 meters. The margin of this advantage is small enough that in practice, there is essentially no real difference. 

As a reference, it is worth noting the different design approaches of the historical counterparts to the PKT(M) used by the hypothetical adversaries to the Soviet Army. In the Bundeswehr, the MG3 was used in a variety of roles, including as a tank coaxial machine gun. In a mounted configuration, the machine gun is normally set to its highest fire rate of 1,200 RPM, but despite the high cyclic fire rate of the MG3 compared to all other machine guns of its class, its practical fire rate was only 150 RPM due to the low heat limit of its rather light barrel. Moreover, due to the constraints of the mounting system in tanks and other armoured fighting vehicles, it was not possible to overcome this shortcoming by periodically swapping out barrels as with infantry guns, and the MG3 was not equipped with a heavy barrel. So despite its high cyclic rate of fire, the MG3 did not actually have a relevant fire rate advantage, and moreover, may have had to run at its heat limit more often when used in armoured vehicles than when it was used in infantry roles due to the inability to swap barrels.

As another point of comparison, the MG34, used in the Wehrmacht during the war as a tank coaxial and bow machine gun, had a rate of fire of 800-900 rounds per minute. Contrary to the popular opinion that the MG34 was retained for coaxial and bow machine guns for German tanks like the Tiger II and Panther despite the appearance of the MG42 due to its unique quick-change barrel mechanism being more suitable for the confined space of an enclosed vehicle, the fact is that the MG34 mount on such vehicles made it impossible to carry out a barrel swap. While barrel swaps were possible in a Pz.III due to the machine gun being mounted by the shroud rather than the receiver, this capability was deleted from later vehicles. In both a rail mount for coaxial machine guns and a ball mount for bow machine guns, the MG34 (with a Panzerlauf) was not only rigidly attached to the mounting frame at the trunnion but also at the rear of the receiver underneath the trigger assembly, making it impossible to rotate the receiver around its hinge to access the barrel without dismounting the machine gun entirely. A heavy barrel was not installed in these MG34s because the machine gun operated on the short recoil principle, and a heavier barrel would have affected the dynamics of the operating mechanism and its rate of fire. As such, these machine guns retained the standard 2 kg barrel, which had a heat limit of 250 shots fired continuously in bursts.

In the U.S Army, machine guns with a low cyclic rate were historically preferred as a technical measure to prevent excessive ammunition expenditure, and in fact, in 1973-1974 when the U.S Army initiated plans to replace the M219, a limit of 400-625 RPM was set as the by the so-called Required Operational Capability and a lower fire rate within the specified range was preferred. The historical preference for a low firing rate can be seen in the M1919 or M37 machine guns which were built with a cyclic rate of fire of 400-500 RPM. The later M73 and M219 machine guns had a marginally higher rate of fire of 500-625 RPM, which was a much more reasonable range. The barrel weighed 2.55 kg, which is good given that it is only 559mm long. Its average cross sectional thickness should therefore exceed that of a PK and MAG 58 by a comfortable amount and reach or even exceed that of a PKT. Moreover, the M73 and M219 were specially designed for enclosed AFVs and was not only exceptionally compact, but it also had a mounting system that permitted quick barrel swaps using a mechanism similar to the MG34, as demonstrated in a U.S Army training film. Overall, the M73 and M219 were ostensibly ideal machine guns for enclosed AFVs and appear to be the top candidates as the best in their class.

However, a major caveat to this impressive capability is that both of these machine guns were plagued by issues that may be charitably described as inconsistent reliability, which may or may not have been design faults, but were nevertheless grounds for their eventual retirement. They were replaced by the M240, a licence-produced version of the FN MAG 60-40 machine gun under a different name.

Outside of the USSR, the MAG was the most successful counterpart to the PKT, and it is perhaps not a coincidence that it shared the closest resemblance in technical characteristics, including rate of fire. The MAG 60-40, the tank coaxial weapon variant of the MAG 58 machine gun, had a rate of fire of 650-950 RPM. Under normal operating conditions, the fire rate is practically the same as the PKT.


The rifling of the PKT(M) barrel has 4 rectangular lands and grooves with one right-hand twist in 240mm. The barrel weighs 3.23 kg which is 0.63 kg heavier than the barrel of a standard PK (2.6 kg) and 0.83 kg heavier than that of a PKM (2.4 kg). The barrel length of the PKT is 722mm, of which 665-666mm is rifled. The standard PK barrel weighs 2.6 kg and has a length of 603mm, of which 550mm is rifled. The PKM barrel (2.4 kg) was noticeably lighter than the PK barrel due to the removal of the fluting and a slight reduction in thickness.

Due to the longer barrel, the PKT fires at a slightly higher muzzle velocity than the PK which had a marginal effect on its effective range. However, this was not the reason why the the barrel length was increased. The primary reason was to match the barrel of the SGMT medium machine gun which was 720mm in length. The SGMT machine gun shared the same barrel length of the SGM it was derived from, and both had very heavy barrels (4.1 kg) as they were medium machine guns whereas the PK was a general-purpose machine gun with a shorter and lighter barrel to optimize it for infantry use. The increased barrel length of the PKT enabled it to achieve the same muzzle velocities as the SGMT when firing the same ammunition, thus ensuring the possibility of replacing the SGMT in older AFVs with the new PKT without any modifications to the gunner's sights. The positive effect on the effective range of the machine gun was merely a bonus.

Because tank gunners do not face problems with dust obscuration and recoil control when using the coaxial machine gun, the combat rate of fire tends to be higher than the rate expected from an infantry machine gunner, but just like their infantry counterparts, tank gunners are still trained to be cognizant of the heat limits of the machine gun. Having a machine gun with a greater heat tolerance permits the delivery of sustained fire for longer periods, and this is highly desirable because the primary purpose of machine guns is the suppression of enemy forces with accurate sustained fire in support of friendly forces. In the assault, this is done to allow the maneuver of friendly forces against the objective, and in the defence, this is done to prevent the maneuver of enemy forces to facilitate their destruction. For tanks, the machine gun fulfills the same role and also serves as a close range alternative to HE-Frag shells with low collateral damage to eliminate soft targets in the open.

Assuming a robust construction, the heat tolerance of a machine gun is usually dependent on the barrel alone. Barrel overheating is a particularly pernicious issue for enclosed AFVs because of the enclosed nature of vehicle and the weak airflow inside them. Moreover, in tank turrets with thick armour, most of the barrel may be enshrouded by the gun mask or the walls of the machine gun port cutout in the turret, exemplified by the T-72A turret shown in the drawing below. The lack of fluting on the PKT barrel like on a PK barrel was most likely influenced by the realization that the lack of airflow inside a tank turret rendered such a feature almost entirely useless.

This problem is intrinsically linked to the armour thickness of the vehicle, and cannot be solved without compromising it by cutting a larger opening or by shifting the machine gun mount further back. The former option is unacceptable for obvious reasons, and the latter option is rather unattractive due to the limited space inside tank turrets. Without an external cooling system of some kind, the only solution to increase the heat tolerance of barrels for machine gun in enclosed AFVs is to drastically increase the cross sectional thickness of the barrel. Having a heavy barrel on the PKT was therefore the most rational design decision given the set of limitations that the Kalashnikov team had to work with.

The barrel of the PK is rated for 200 shots fired continuously and 400 shots fired continuously in bursts, meaning that one or two 200-round boxes can be depleted before a barrel swap is mandatory in order to avoid premature wear of the barrel and prevent a drop in accuracy from overheating. A manual on the operation of the PK family of machine guns defines a short burst as lasting for 10 rounds and a long burst as lasting for 30 rounds. This is practically the same as the 20 or 30-shot burst lengths specified for other machine guns in foreign armies.

The thicker and longer barrel of the PKT had the same heat limit of 500 shots fired continuously in bursts. Because the PKT is fed with 250-round boxes, this is equivalent to a continuous burst fire limit of two ammunition boxes. With a practical rate of fire of 250 RPM, a single ammunition box will last for a full minute of continuous burst fire. This is good performance for a coaxial machine gun and it is particularly good when compared to weapons like the MG3. The FN MAG 60-40 has a 2.5 kg barrel, standardized with the infantry variant, and has a heat limit of 200 rounds fired continuously or 400 rounds fired in bursts, matching the PK and PKM which have barrels of a very similar weight. The M60 machine gun had a heat limit of 400 shots fired continuously in bursts, but at a lower practical fire rate of 200 RPM compared to the 250 RPM of the PK and PKT.


1,2 - LPS light ball from different years of manufacture, 3,4 - T-46 tracer, 5,6 - B-32 armour-piercing incendiary

On all Soviet tanks from the T-55A to the T-80U and in modern Russian tanks like the T-90A, the PKT or PKMT would be fed with 250-round boxes of belted ammunition linked in 50-round segments. Each 250-round box weighs 9.4 kg fully loaded.

The standard combat load of 7.62mm ammunition was 2,000 rounds for most Soviet AFVs. Proprietary high capacity boxes did not exist for the machine guns of any Soviet armoured vehicle until the advent of the BMP-1 which had a special 2,000-round container for its coaxial machine gun.

The practice of using standard large capacity ammunition boxes for the coaxial machine gun dates back to the invention of the triple-stack 63-round pan magazine for mounted DP machine guns in 1928 and its subsequent use in DT and DTM machine guns in Soviet tanks to facilitate longer sustained fire. When the DTM was replaced by the SGMT medium machine gun, it was fed with 250-round boxes that were also standard for wheeled and tripod-mounted SG-43 machine guns. This did not change when the Soviet Army transitioned to the PK series, as the 250-round boxes for the PKT were also standard for tripod-mounted PKS machine guns and for PKB machine guns on armoured personnel carriers.

In the Soviet Army, the three primary ammunition types used in PKT machine guns were:

  • 57-N-323S light ball round with LPS bullet
  • 7BZ-3 API (armour-piercing incendiary) round with B-32 bullet
  • 7T2 API-T (armour-piercing incendiary tracer) round with T-46 bullet

The three bullets are shown in the drawing below in this order, from left to right.

The components are:

  1. Tombak-clad steel jacket
  2. Lead-antimony alloy
  3. Steel core
  4. Tracer cup
  5. Tracer element
  6. Incendiary charge

All of the cartridges had steel cases. The use of steel for the cartridge cases instead of brass was a strategic decision that was related to the expense and availability of the two materials.

Usually, a mixture of all three ammunition types are linked into standard ammunition boxes. A typical belt would be sorted into groups of three, each group having two non-tracer rounds and one tracer round (2:1 ratio). The order of bullet types would be as follows.

Ball - Ball - T - Ball - Ball - T - Ball - AP-I - T

For comparison, a typical mixture for M73 machine guns is Ball to Tracer rounds in a 3:1 ratio and the preferred mixture for M240 machine guns is Ball to Tracer in a 4:1 ratio. The higher concentration of bullets with an incendiary payload in a standard Soviet belt permits easier fire correction at long range, not to mention that it also slightly enhances the destructive effect on the target by increasing the probability of starting a fire. 

It is worth noting that the belt composition for an infantry PK or PKM would consist of 3 or 4 ball rounds to 1 tracer or AP-I round. There was no fixed rule on how a belt should be ordered. Compared to these infantry machine guns, a PKT or PKTM would have a much higher concentration of ammunition with firestarting potential, and a much shorter interval of tracers for fire correction, supplemented by the higher fire rate, which increases the density of tracers rounds for a given burst time.

Overall, 7.62x54mm ammunition outperformed 7.62x51mm ammunition to an extent, but remained firmly within the same performance class.

LPS (Ball)

The LPS bullet is a ball bullet with a mild steel core. The bullet has a weight of 9.6 g and has a muzzle velocity of 855 m/s. Between the steel core and the jacket is a lead filler. Its purpose is to help seat the core, but it also functions as additional mass at the circumference of the bullet which increases the rotational inertia of the bullet. This allows the bullet to remain spinning at a sufficient rate to remain stable at longer distances than would be otherwise possible without the lead filler.

The LPS entered service in the Soviet Army in the 1953 as the universal ball bullet for all purposes. At the same time, the production of ammunition with L bullets (light ball with lead core) and D bullets (heavy ball with lead core) was discontinued. The standardization of bullets had a significant economic effect as it allowed Soviet ammunition production facilities to be optimized for a single product, and the shift to a new ball bullet with a steel core also brought long-term cost savings by conserving lead.

Moreover, the LPS bullet had superb ballistic properties that allowed it fulfill the function of heavy ball bullets while having a bullet of the same weight as light ball bullets. The weight of the LPS bullet, 9.6 grams, was identical to the L obr. 1908/30 light ball bullet with a lead core which had a muzzle velocity of 855 m/s when fired from an SG-43 or SGM medium machine gun. The D obr. 1930  heavy ball bullet weighed 11.8 grams and had a muzzle velocity of 800 m/s when fired from an SG-43 or SGM. The maximum range of the L bullet was 3,800 meters whereas the D bullet achieved a maximum range of 5,000 meters. The maximum range of the LPS bullet when fired from an SG-43, SGM, or PKT at a nominal muzzle velocity of 855 m/s is 4,600 meters.

The L bullet was optimized for short range fire from light machine guns and infantry rifles, having a higher velocity that facilitated firing at point targets with iron sights. The D bullet was optimized for long range fire from medium machine guns against area targets using indirect fire techniques. However, the role of heavy bullets was deemed obsolete when actual combat experience during the early stages of the so-called Great Patriotic war showed that long range fire from machine guns was a waste of ammunition which was only exacerbated if indirect fire was used. However, light and heavy bullets were still issued for DP light machine guns and SG-43 medium machine guns respectively with the expectation of fulfilling their theoretical roles. The appearance of the LPS bullet made the distinction between light and heavy bullets redundant.

Due to the large quantities of L and D ammunition stockpiled, they remained in service after 1953 but were relegated to use in training. By the time the PKT replaced the SGMT in the Soviet Army, LPS ammunition had been firmly established as the new standard. The production of cartridges with LPS bullets was discontinued in 1988.

Relative to other bullets of its class, the LPS design is not particularly heavy, despite its good energy retention at long range. The weight of the LPS bullet is slightly less than the 7.62x51mm M80 ball bullet, which has a nominal weight of 147 grains (9.52 grams) but can weigh up to 9.66 grams (149 grains). The M80 bullet is a bimetallic bullet with a cupronickel jacket and a lead core, and is 24.2mm long. Because the core of the LPS bullet is made of steel, which is less dense than lead, the bullet had to be significantly longer (32.25mm) to be of a similar weight, and by a combination of its greater elongation and a very similar weight, the LPS bullet has a superior ballistic coefficient compared to the M80 bullet. For comparison, the M80 bullet has a maximum range of 3,930 meters when fired at a nominal muzzle velocity of 856 m/s, which is almost 700 meters less than the LPS bullet. The M59 ball bullet which the M80 replaced had a mild steel core like the LPS bullet, but its ballistic coefficient was still almost identical to the M80 to ensure direct interchangeability for sighting purposes, and as such, no noticeable improvement in the flatness of the trajectory was gained. This is reflected by its maximum range of 3,820 meters when fired at a nominal muzzle velocity of 856 m/s, which is slightly shorter than M80.

Officially, the use of a mild steel core in the LPS bullet only negligibly improved its obstacle penetration performance compared to the L bullet obr. 1908/30, but it drastically increased the maximum range at which steel helmets could be pierced. The LPS ball round is rated to perforate a generic steel helmet (most likely SSh-40) at a range of 1,770 meters and it defeats generic body armour (most likely a flak vest) at a range of 1,200 meters. For comparison, the D obr. 1930 heavy bullet was rated to pierce a Soviet steel helmet at a distance of 1,400 meters, and the 7.62x51mm M80 ball round is only rated to penetrate one side of a U.S Army M1 steel helmet at 800 meters. At a distance of 1,000 meters, an LPS bullet will perforate a compacted snow bank with a thickness of 700-800mm or an earthen barrier with a thickness of 250-300mm. The bullet will also perforate a dry pine plank with a thickness of 200mm at a range of 1,200 meters. A brick wall with a thickness of 100-120mm is perforated at a distance of 200 meters.

The table below shows the thicknesses of RHA and 5083 aluminium that can be perforated by this bullet at a variety of ranges and slopes.

In the mid-1980's, it was determined that the proliferation of the new-generation PASGT personal protection equipment among NATO forces significantly reduced the effectiveness of existing ball cartridges with an LPS bullet. However, the impetus of this research project is not entirely clear given that the PASGT vest and helmet were only capable of stopping small shell fragments and were completely insufficient against ordinary LPS ball bullets at any meaningful range. Even the NATO standard M80 ball round with a lead core had no issues perforating the 13 plies of Kevlar that formed the vest. It is likely that comprehensive information on the characteristics of the PASGT kit was not available in the USSR at the time.

The new LPS bullet with a heat-treated steel core entered service in 1986. Its ballistic characteristics were identical to the older LPS bullet it replaced, and differed only in the increased armour penetration power.

B-32 (AP-I)

The original B-32 bullet introduced into service in the year 1932 was an armour-piercing incendiary bullet with an incendiary pellet placed in a cavity in the nose of the bullet, ahead of the pointed steel core. An aluminium, magnesium and barium nitrate compound is used for the incendiary charge, which weighed 0.26 grams. The steel core, which weighs 5.38 grams, has a diameter of 6.09mm and a length of 30mm. The total length of the bullet is 36.83mm, and the total weight is 10.4 grams. Like the LPS bullet, the steel core is surrounded by a lead filler. The closest foreign counterpart to the B-32 bullet is the .30-06 caliber AP M2 bullet, which weighs 10.8 grams, has a total length of 35.3mm and has a steel core with a diameter of 6.17mm and a length of 27.4mm.

The table below shows the thicknesses of RHA and 5083 aluminium that can be perforated by this bullet at a variety of ranges and slopes.

As the table shows, the penetration of the B-32 bullet into RHA steel reaches 0.7 inches (17.78mm) at 0 degrees at its muzzle velocity of 855 m/s when fired from a PKT. For comparison, the .30-06 caliber AP M2 bullet perforates 0.68 inches (17.27mm) of RHA steel at 0 degrees at its muzzle velocity of 845 m/s when fired out of an M1919 or M37. A direct comparison between these two bullets is valid because both were evaluated by the U.S military under the Navy Criterion.

In 1954, the Soviet Army adopted the B-32M armor-piercing incendiary bullet to replace the B-32 bullet mod. 1932. The new design was distributed under the same old name of B-32, but for the sake of clarity, it will hereby be referred to as B-32M. The main difference of the new B-32M bullet was an additional incendiary charge placed behind the steel core to supplement the incendiary charge in the nose of the bullet. The presence of an incendiary charge behind the steel core drastically increases the incendiary effect produced behind an armour plate perforated by the bullet.

The weight of the B-32M bullet is 10.37 grams. The difference in weight from the original B-32 is insignificant and the ballistics of the new bullet remained identical.

T-46 (T)

The T-46 tracer bullet is designed purely for fire correction purposes. A large tracer element dominates the majority of the volume in the bullet, leaving only a lead filler in the tip. The bullet weighs 9.6 grams. 

When fired, the combustion of the propellant powder charge ignites the tracer composition which burns during the flight of the bullet, giving a bright luminous trail, clearly visible during day and night. The bullet head is painted green. However, contrary to a persistent myth related to the green colour code on the bullet, the tracer colour is not green but red. The older T-30 tracer bullet, which the T-46 replaced, had a colour that was officially white and was actually white with a greenish tinge.

The bullet tracer is guaranteed to burn to a distance of 1,000 meters. This was an improvement over the T-30, which provided a trace only up to a distance of 800 meters. The tracing period is up to 3 seconds, which nominally allows the bullet to form a visible trace beyond 1,000 meters, but reliable tracing is not provided beyond 1,000 m due to a variety of factors. 

While burning, the tracer flare interacts with the flow of air at the tail of the bullet, filling the low-pressure zone to allow more of the flow to merge rather than form a turbulent wake, thus reducing the tail drag to some extent. The resulting reduction in drag, together with a streamlined form, allowed the T-46 bullet to maintain a trajectory similar to an LPS or B-32 bullet despite the gradual burn-off of the bullet mass, and therefore, the loss of sectional density. Out to 1,000 mters, the reduction in drag gives the T-46 bullet a flatter trajectory than LPS and B-32, so gunners need to be aware that the fall of a burst may be below the impact of the tracers, especially at closer ranges. As the tracer element eventually burns out near the end of its tracing period, the divergence of the bullet trajectory relative to LPS and B-32 reverses. Incidentally, it is worth noting that due to inherent variations in tracer weights due to factory filling margins, the tracing period and intensity can vary slightly, with a corresponding variation in the effect on the streamlining of the bullet. This worsens its dispersion compared to ball and AP-I bullets.

In 1969, work began on the modernization of the T-46 bullet. The new model was designated T-46M and adopted in 1974. The lead filler was enlarged and the size of the tracer element was downsized, and the overall weight of the bullet decreased to 9.4 grams. The same tracing range was maintained by switching to a slower-burning tracer compound, thus achieving the same burn time of 3 seconds. The tracer colour remained red. Moreover, the tracer had a delayed ignition so that it only began to burn after travelling 80-120 meters downrange of the muzzle. This helped the firing position of the machine gun to remain concealed. The new bullet matched the ballistic trajectory of LPS bullets more closely.

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