5 in/38 naval gun ammunition 5 in/38 Calibre Projectile, Common 5 in/38 HE-PD

general reliability, handling and accuracy were rated as excellent. A measure of its importance to the US Navy can be seen in the fact that it was the first gun for which Proximity (Variable Time - VT) fuzes were developed and issued. Few 5 in 38 calibre guns now remain in use with the US Navy but the type is still widely used by many other navies, along with many different types of ammunition, although the variety of mountings has now been reduced to, at the most, four types. Description The ammunition intended for use in the 5 in 38 calibre dual-purpose (surface target and anti-aircraft) gun is semi-fixed. All rounds use a flat-based forged steel projectile with a single wide copper drive band allied with a cartridge case containing either a Full or Reduced Charge. Nose fuzes are normally protected by a domed cover until just before loading. The projectile weight for all types is around 25 kg. The projectile types are listed below but the cartridge cases and charges are common to most so details are provided here. The brass cartridge cases are straight-sided and rimmed, with a No 13 or No 48 electrical primer threaded into the base; the igniter tube runs virtually the entire length of the case interior. At the top of the propellant, which is held in position by a wad, is a distance-piece. The case mouth is kept closed by a case plug which is removed before loading. There are four propelling charges, using one or other of three different case mark numbers. They are as follows: D272, Full Charge - Case Mark number 5, 8 or 10 containing 6.9 kg of SPDN-BE propellant D264, Full Charge - Case Mark 10 containing 7.8 kg of Universal propellant D274, Full Charge - Case Mark number 5 or 10 containing 6.9 kg of SPDF-BE propellant D282, Reduced Charge - Case Mark number 5 or 10 containing 1.6 kg of SPDN-U or SPDN-Y propellant. As a range table guide, the muzzle velocity for Full Charge when firing a nominal 24.7 kg projectile is 762 m/s. Maximum range against surface targets is 16,500 m, while for air defence the ceiling is 11,400 m. The Reduced Charge produces a muzzle velocity of 350 m/s with the same weight of projectile. The types of 5 in 38 calibre projectile are as follows: 5 in/38 Calibre Projectile, Common Although intended for use primarily against naval or other surface targets this projectile can be used as an anti-aircraft projectile; it approximates to the APC-T land equivalent. There are three types, the Mk 32, Mk 38 and Mk 48, all of which are basically similar. All use a forged steel body with an armour-piercing tip hooded behind a light-alloy streamlined ballistic cap. The centre of the penetrator body contains a 930 g Explosive D (ammonium picrate) burster charge. The flat base of the projectile has a base plug into which is threaded a base-detonating fuze which is intended to function only after the projectile has penetrated the target armour; the projectile is intended to penetrate a thickness of armour at least one-third of its calibre, that is approximately 42 mm. To provide an impact marker for spotting purposes the hollow interior of the ballistic cap contains a marker dye container. Available dye colours are orange, red, blue and green. This projectile is normally fired using the Full Charge only. The nominal muzzle velocity is then 792.5 m/s. Projectile weight is 25 kg and length 526 mm. 5 in/38 High Explosive Projectiles There are numerous variants of the basic 5 in 38 calibre high-explosive projectile, all of which are essentially the same yet vary according to the presence or absence of a cavity in the base to accommodate a base fuze or the type of steel used for the body (all body types use ductile steel while the Mk 51 and 66 use high-fragmentation steel). All body types have the same basic outline, are 533 mm long and have a nominal weight of 25 kg. These projectiles may use either Full or Reduced Charges. As a general guide, base detonating projectiles are filled with Explosive D (ammonium picrate), while point detonating projectiles use Composition A-3 (RDX/Wax 91/9). 5 in/38 Anti-Aircraft Common - AAC This uses a mechanical time fuze (typically a Mk 349 Mod 1), fitted to the nose along with an auxiliary detonating fuze located in a cavity behind the nose fuze, and a base detonating fuze (typically a Mk 31 or M91A2 ). The AAC body types likely to be encountered are the Mk 35, 49, 52 and 56, all of which contain 3.4 kg of Explosive D (ammonium picrate) - the Mk 52 may also be encountered filled with 3.8 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 HE-MT This is essentially similar to the AAC but lacks the base-detonating fuze facility. Where appropriate the base fuze cavity is closed by a threaded plug. The body types involved are the Mk 35, 47, 49 and 51, all containing 5.5 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 HC Intended for use against surface targets, this type of projectile uses a point-detonating fuze, an auxiliary detonating fuze located in a cavity behind the nose fuze and a base-detonating fuze. The HC body types likely to be encountered are the Mk 35, 49 and 52, all of which contain 3.4 kg of Explosive D (ammonium picrate) - the Mk 52 may also be filled with 3.8 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 HE-PD This is essentially the same as the HC but lacks the base detonating fuze. Where appropriate the base fuze cavity is closed by a threaded plug. The body types involved are the Mk 35, 47, 49 and 52, all containing 3.4 kg of Explosive D (ammonium picrate), and the Mk 51 or 66 containing 5.5 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 VT This projectile uses a radio proximity fuze which may or may not have a self-destruct element. With this projectile the base fuze hole is plugged. Body types likely to be encountered are the Mk 34, 35, 47, 49, 93 and 94, all containing 5.5 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 HE-CVT This is fitted with only a radio proximity fuze (an infra-red proximity fuze was used at one time but was withdrawn) which is normally fitted with a fuze liner for safety. The body types likely to be used are the Mk 35, 47, 49 and high-fragmentation Mk 56 and 66. All contain 5.5 kg of Composition A-3 (RDX/Wax 91/9). 5 in/38 Calibre Projectile, Illuminating This is a conventional illuminating round. There are four types, the Mk 30, 44, 50 and 87. The latter two use the Mk 11 illuminating load which weighs 7.39 kg and produces 600,000 candlepower for 50 seconds. The other two use the earlier Mk 4 Mod 0 illuminating load which weighs 7.68 kg and produces 275,000 candlepower for 60 seconds. In both cases the illuminating load is ejected from the projectile base by a 77.8 g black powder charge located behind the nose-mounted mechanical time fuze. The illuminating load (which uses 1.344 kg of powdered magnesium mixed with an oxidiser) then descends suspended from a 940 mm parachute. The Mk 30 and Mk 44 illuminating projectiles both weigh 25.08 kg and are 509.8 mm long. The Mk 50 and 86 both weigh 25.06 kg and are 528.1 mm long. Full or Reduced Charges can be used. 5 in/38 Calibre Projectile, Chaff Chaff projectiles are used as a basic Electronic CounterMeasure (ECM), by filling a volume of air with a large number of small metallised glass fibre needles. These produce a large radar cross-section to confuse enemy radars or missiles. The Mk 78 uses a Mk 21 (S-band) chaff load while other projectiles may use Mk 15 (X-band) or Type A (S-band) loads. Chaff projectiles have their body interiors optimised in volume to accommodate the chaff payloads and use mechanical time fuzes such as the Mk 349 Mod 0, sometimes with the addition of an auxiliary detonating fuze. Payloads are ejected through the projectile base by a small ejection charge located behind the nose-mounted fuze(s). A typical 5 in/38 Chaff projectile weighs 25.1 kg and is 528 mm long. The nominal muzzle velocity is 796 m/s and maximum range is 15,790 m. Full or Reduced Charges can be used. 5 in/38 Calibre Projectile, WP/Smoke This projectile uses an unusual smoke production system, in that a M5 canister containing 3.2 kg of White Phosphorus (WP) is ejected from the base of the carrier projectile once the nose-mounted Mk 73 point detonating (over land), or Mk 74 mechanical time (over sea) fuze has functioned. The canister, which is 305 mm long, is ejected by the internal pressures created by a 124.4 g expulsion charge located beneath the fuze well. The same charge also initiates a delay element in the top of the canister. After the delay is complete, the delay element detonates a burster tube running through the centre of the canister and breaks it open to disperse the WP. The WP then creates a grey/white screening smoke cloud which, in still air conditions, is approximately 45 m in diameter and persists for up to 7 minutes. With this projectile the WP is coated with synthetic rubber to improve its shelf life - the coated product is called TWP (plasticized white phosphorus). The projectile weighs 24.7 kg and is 508 mm long. It is normally fired using Full Charge only. Muzzle velocity is then 792.5 m/s. Practice projectiles (5 in/38) with inert fillings and dummy fuzes have also been produced along with completely inert handling training or `ramming' rounds. Authorised fuzes Several types - see text Equivalent rounds BRAZIL BRAZIL Manufacturer FI Indústria e Comércio Ltda Type: HE-CVT, HE-MT, HE-PD, HE-MT, HE-VT-SD, AAC, BL-T/P (Prac with Tracer) Description: Standard US specifications SPAIN Manufacturer DEFEX SA Type: HE-VT, HE-MT Description: Standard US specifications Manufacturer EXPAL SA Type: HE-VT, HE-MT Description: Standard US specifications except that propellant is 7 kg of single-base flashless GSB-120 TURKEY Manufacturer Makina ve Kimya Endüstrisi Kurumu ( MKEK ) Type: HE-AAC (MKE MOD 205) and TP (MKE MOD 202 BL/P) Description: Standard US specifications. Production as required