Oerlikon KBA

Oerlikon KBA 25 mm
Oerlikon KBA 25 mm
	Oerlikon KBA 25mm Automatic Cannon
Type	Autocannon
Place of origin	Switzerland
Service history
In service	Mid 1970s – present
Used by	See operators
Production history
Designer	Oerlikon-Bührle
Manufacturer	Rheinmetall AG
No. built	4,000+
Specifications
Mass	112 kg (247 lb)
Length	2,806 mm (110.5 in)
Barrel length	2,173 mm (85.6 in)
Width	263 mm (10.4 in)
Height	283 mm (11.1 in)
Shell	NATO 25×137mm
Caliber	25 mm
Rate of fire	Burst: 600 rds/min; Maximum: 700 rds/min; Programmable: 175-300 rds/min
Muzzle velocity	1,100 m/s (3,600 ft/s); 1,400 m/s (4,600 ft/s)
Effective firing range	3,020 m (9,910 ft)
Maximum firing range	5,850 m (19,190 ft)

The Oerlikon KBA is a 25 mm (25×137mm) autocannon, developed as a close range multipurpose weapon in the mid-1970s for the mechanized battlefield, originally made by Oerlikon-Bührle (now Rheinmetall AG). It is a positively locked, gas-operated cannon with a rotating bolt head and a dual-belt selective feed system taking a 25 mm cartridge. The nominal rate of fire in burst mode is 600 rounds per minute but it can be adjusted electronically and reduced from single shot to selectable range between 175 to 300 rounds per minute.^[1]

Due to its firepower, its range of ammunition and its "Instant Ammunition Selection Device" (IASD), which allows the gunner to easily switch between armor-piercing and high-explosive rounds, the KBA cannon can engage lightly armoured vehicles, infantry, anti-tank positions, helicopters, combat aircraft and ships.

Description[]

The Oerlikon KBA 25 mm is a fully automatic cannon based on the proven gas-operation principle with a rotating bolt head similar to the Mauser M 98 or M16 and double belt feed for the ammunition.

The KBA offers a wide range of firing modes: single shot, programmable rapid single shot with a rate of fire of up to 200 rds/min, and full automatic fire at 600 rds/min. The cannon functions, such as cocking and firing, are electrically actuated by a remote control unit or manually in auxiliary mode by means of a hand crank and a trigger pedal.

The Oerlikon KBA 25mm cannon has been designed for integration in various types of mounts, small size and low weight offering various integration possibilities such as:

Human-operated or remote controlled turrets on IFVs and APCs
Air defence gun mounts
Naval mounts^[2]
Helicopter mounts

The various types of available ammunition combined with the unique Instant Ammunition Selection Device and selectable rates of fire support any type of operational use.

History[]

At the turn of 1964-65, the United States started the ambitious Bushmaster project started as an offshoot of the US Army's MICV-65 program that was attempting to introduce a new infantry fighting vehicle to replace their existing M113 armored personnel carriers, the Bushmaster project aimed to create small-caliber cannon for the US Army.

The Bushmaster project were intended to meet the requirements for the armament of infantry fighting vehicles (IFV) of the 80's and 90's:

Ammunition performance: 25 mm armour steel, 60° (NATO) angle of impact, 1000m range, corresponding to the armour of a well-armoured infantry fighting vehicle;
Instant ammunition selection: for engagement of different targets;
Selectable firing mode: Accurate single-shot, bursts with a rate of fire of more than 550 rds/min for engagement of aircraft;
Compact structure: with low weight for installation in gun turrets of APC's;
Simple to operate and service: in the hands of infantry.

At the early stage of American program, one of the companies involved in the development of automatic guns of the Bushmaster program was TRW Inc. (Thompson Ramo Wooldridge Inc.) who entrusted with the development of a 25mm weapon.^[3]

The TRW project was under the leadership of engineer Eugene Stoner, the author of the famous M16 rifle, lead to the development of a 25 mm automatic cannon under the internal designation "TRW model 6425", an ordinary system developed around the experimental 25x137 mm cartridge with automatic gas-operated and locking the barrel with a rotary bolt.^[4]

TRW Model 6425 Automatic Cannon

TRW's requirement for the 25mm project where that the gun had to be fully automatic and actively locked, be operated by gas and with rotating bolts, use a dual-belt selective feed system, and be able to switch quickly and easily between different type of ammunition.

Oerlikon-Bührle assumed responsibility for developing the ammunition 25x137mm and interior ballistics for it.^[5]

The first prototype was produced in 22 months and began test firing in November 1965 from an Ml 14 vehicle, in December the prototype was fired from an Austrian Armored Personnel Carrier. An early version was tested by a number of countries including Great Britain and France.

At the beginning of 1967, technical tests and firing trials were carried out with two TRW-6425^[6] prototype cannons followed by the first demonstrations for a NATO country.

The early configuration was tested several times at Aberdeen Proving Ground, included was a Military Potential Test from March 1968 to March 1970.

Before the U.S. tests were completed, at the end of 1969 TRW ceased work on the TRW-6425 cannon and in the same year the company Philco-Ford Aeronutronic Division began work on the weapon when TRW sold the rights of the gun project to them.^[7]^[8]^[9] At least six TRW-6425 automatic cannons were built.^[8]

The PFB-25 has been selected as one of the self powered gun for the U.S. Army Vehicle Rapid Fire Weapons System (Bushmaster), hence the name PFB-25 which stands for Philco-Ford Bushmaster 25mm.^[10]

Since then, Philco-Ford has further developed their version, the PFB-25,^[10] in the same period Oerlikon started the project "KBA" series which is similar to the 25mm cannon TRW-6425.^[8]

Oerlikon KBA 25mm Part Description

In the Oerlikon project, which received the designation KBA (where "K" is kanone; "B" is a 25 mm caliber, "A" is a design model in a given caliber), several principles were combined in order to refine the project.

The original American design of TRW-6425 was reworked, perhaps only the originally laid down cartridge of 25x137 mm and the method of blocking the chamber by turning the bolt, which was a novelty for the development of Oerlikon, remained from it, earlier systems had sliding bolts with locking lugs. Developed by Eugene Stoner, the classic TRW-6425 cannon automatic gas valve drive has also undergone global changes.^[3]

In the trials, however, the American prototypes PFB-25 displayed a number of basic functional deficiencies.^[11] This persuaded Oerlikon-Bührle to undertake their own development work to effect system modifications, which then resulted in the required functional reliability and enabled the trials to be completed successfully in 1970. When the first prototype cannons became available, suitable gun turrets had also to be provided.

Example of Oerlikon KBA installed on Italian VBM Freccia (IFV) wheeled in use by the Italian Army.

The complete system, cannon, hand-driven turret and ammunition underwent detailed firing trials between 1969 and 1971.

Special new development efforts were devoted to improve functional reliability, durability and firing precision, and in 1971 sufficient progress had been made for the weapon system to fulfill the strict specifications laid down, and to be delivered to the Netherlands.

Within the framework of the product support service Oerlikon improves the product and adapts it regularly to the latest requirements. An important step forward was made in 1982/83 when the ammunition penetration performance range of the 25 mm APDS-T (sub-caliber) round was increased 150% from 1000 to 2500 m.

The refined project KBA from Oerlikon, such as high rate of fire, reliability, ammunition performance, good safety record, dual belt feeder with first-round response, no external power requirement and simple maintenance lead to a considerably increasing interest in the Oerlikon KBA 25 mm cannon in years coming.

Ammunition[]

A wide range of ammunition has been developed for this weapon specifically developed to engage and defeat both ground and air targets.

KBA 25mm on Dutch YPR-765 in Afghanistan

The ammunition complies with all handling and operational safety requirements according to MIL-STD’s, and was subjected to intensive trials by NATO member countries prior to its introduction and standardization as NATO 25mmx137 ammunition.

The current 25x137mm ammunition family consists of six combat and two training rounds:

APFSDS-T: armour-piercing fin stabilized discarding sabot with tracer, for use against armoured ground targets
APDS-T: armour-piercing discarding sabot with tracer, for use against armoured ground targets
FAPDS-T: frangible armour-piercing discarding sabot with tracer, for use against air, ground and urban targets
TPDS-T: target practice discarding sabot with tracer, a short range trainer for the above sub-calibre types
SAPHEI-T: semi-armour-piercing high explosive incendiary with tracer, for use against well protected targets
HEI-T: high explosive incendiary with tracer, for use against lightly protected targets
MP-T: multipurpose with tracer
TP-T: target practice with tracer, for raining with the above full calibre types

Mounting & Weapon Station[]

OTO Melara 25/80 with Oerlikon KBA 25mm (manned configuration).

ASELSAN[]

Turkish made Aselsan STOP stabilized weapon station can be fitted with a Oerlikon KBA.^[12]

Turkish made Aselsan remote controlled weapon station is developed primarily against armored land targets.^[13]

LEONARDO[]

OTO-Melara has developed two-man turret, for armored vehicles called HITFIST. The turrets are designed to mount a 25mm Oerlikon KBA or 30/40mm ATK Mk44 autocannon.

The main armament may mount a co-axial machine gun. A variant allows the operator to aim and fire anti-tank missiles. Operators include Italy, Poland and Romania.^[14]

Also OTO-Melara has developed a single OTO-Melara 25/80 KBA stabilized weapon station, electric servo-drive assisted for naval application, available in the unmanned or manned configuration.^[14]

Oerlikon KBA 25mm installed on LEONARDO OTO-Melara 25/80 RCVS

Operators[]

Current operators[]

Italy
- Italian Navy
  - LHD Trieste Aircraft Carrier
  - CVH 550 Cavour Aircraft Carrier
  - San Giorgio-class Amphibious transport dock
  - FREMM Multipurpose frigate
  - Horizon-class Frigate
  - Thaon di Revel-class Offshore patrol vessel
  - Comandanti-class Patrol vessel
  - Cassiopea-class Patrol vessel
  - Sirio-class Patrol vessel
  - Minerva-class Corvette
  - Vulcano-class Logistic support ship
  - Etna-class Replenishment oiler
  - Stromboli-class Replenishment oiler
  - Elettra Navy SIGINT vessel
- Italian Coast Guard
  - Diciotti-class Offshore patrol vessel
- Italian Army
  - IFV Freccia Infantry Fighting Vehicle
  - IFV Dardo Infantry Fighting Vehicle
  - SIDAM 25 Self-propelled anti-aircraft gun (decommissioned)

Belgium
- AIFV-B-C25 with a 25 mm Oerlikon KBA-B02 cannon
Bangladesh
- Leader-Class Offshore patrol vessel
- Sobuj Bangla-class Inshore patrol vessel