View source for 25 mm caliber

{{Short description|Specific size of autocannon ammunition}}
{{Multiple Issues|
{{No footnotes|date=May 2021}}
{{More citations needed|date=April 2025}}
}}
[[File:US Navy 090129-N-4774B-008 Gunner's Mate 2nd Class Nicholas Brassard inspects rounds for the MK-38 25mm machine gun system.jpg|thumb|300px|25×137mm M793 target practice with tracer (TP-T) rounds for the MK-38 being inspected]]

'''25 mm caliber''' is a range of [[autocannon]] ammunition. It includes the [[NATO]] [[NATO cartridge|standardized]] Swiss 25×137mm, the Swiss 25×184mm, the Soviet 25x218mmSR, and the Chinese 25×183mmB.

==Usage==
The 25&nbsp;mm round can be used for anti-materiel or [[Anti-personnel weapon|anti-personnel]] purposes. In the anti-personnel role, a 25&nbsp;mm  [[High explosive|HE]] rounds can kill large numbers of opposing troops either in the open or in light fortifications. In the anti-materiel role, a 25 mm weapon armed with [[Armor-piercing shot and shell|armor-piercing]] rounds can disable many types of aircraft and ground vehicles, including some [[main battle tank]]s.

The [[United States armed forces|US military]] uses 25 mm weapons in their [[AV-8B Harrier]], [[AC-130 gunship]], [[M2 Bradley]], [[LAV-25]], [[F-35 Lightning II]] and as a standard ship-based munition in the [[Mk 38]] autocannon.

==Types of 25 mm ammunition==
[[File:Japanese 25 x 163 mm ammunition.jpg|thumb|Japanese 25×163mm ammunition from a post-war US technical manual]]
[[File:M791-APDS-T.png|thumb|A diagram of the M791 25×137mm round]]

Several sub-types of the NATO 25&nbsp;mm [[ammunition]] are available—the most common being [[Armor-piercing shot and shell|armor-piercing]], high-explosive, [[Sabot (firearms)|sabot]], [[Tracer ammunition|tracer]], and practice rounds. [[Cartridge (weaponry)|Cartridge]]s are usually composed of a combination of the aforementioned categories. For example, the M791 is an armor-piercing discarding sabot with tracer (APDS-T) round. It is used against lightly [[Armoured fighting vehicle|armored vehicles]], [[self-propelled artillery]], and aerial targets such as [[helicopter]]s and slow-moving fixed-wing aircraft.

==25 mm weapons==

===Current weapons===

{| class="wikitable"
! style="width: 100px;" | Weapon
! style="width: 150px;" | Country of origin

! style="width: 150px;" | Designer
! style="width: 100px;" | Cartridge
! style="width: 150px;" | Type
|-
| [[Oerlikon KBA]]
| {{flag|Switzerland}}
| [[Rheinmetall AG]]
| 25×137mm
| [[Autocannon]]
|-
| [[M242 Bushmaster]]
| {{flag|United States}}
| [[Hughes Helicopters]]
| 25×137mm
| [[Chain gun]]
|-
| [[GAU-12 Equalizer|GAU-12/22 Equalizer]]
| {{flag|United States}}
| [[General Electric]]
| 25×137mm
| [[Rotary cannon]]
|-
| [[Giat M811|GIAT M811]]
| {{flag|France}}
| [[GIAT Industries]]
| 25×137mm
| Autocannon
|-
| [[Oerlikon KBB]]
| {{flag|Switzerland}}
| [[Rheinmetall AG]]
| 25×184mm
| Autocannon
|-
| [[Oerlikon KBD]]
| {{flag|Switzerland}}
| [[Rheinmetall AG]]
| 25×184mm
| Autocannon
|-
| [[Type 61 25mm AAA guns|Type 61]]
| {{flag|China}}
|
| 25×218mmSR
| Anti-aircraft autocannon
|-
| [[Type 95 SPAAA]]
| {{flag|China}}
|
| 25×183mmB
| Anti-aircraft autocannon
|-
| [[ZPT-90]]
| {{flag|China}}
| 
| 25×183mmB
| Autocannon
|}

===Historical weapons===

{| class="wikitable"
! style="width: 100px;" | Weapon
! style="width: 150px;" | Country of origin

! style="width: 150px;" | Designer
! style="width: 100px;" | Cartridge
! style="width: 150px;" | Type
|-
| [[25 mm Hotchkiss anti-aircraft gun]]/[[Type 96 25 mm AT/AA gun]]
| {{flag|France}}
| [[Hotchkiss et Cie]]
| 25×163mm
| Anti-aircraft autocannon
|-
| [[25 mm Hotchkiss anti-tank gun]]
| {{flag|France}}
| [[Hotchkiss et Cie]]
| 25×193.5mmR
| [[Anti-tank gun]]
|-
| [[25 mm automatic air defense gun M1940 (72-K)|25&nbsp;mm M1940 anti-aircraft gun]]
| {{flag|Soviet Union}}
| [[Mikhail Loginov]] and [[Lev Loktev]]
| 25×218mmSR
| Anti-tank gun
|-
| [[Bofors 25 mm M/32|25 mm Bofors M/32 anti-aircraft gun]]
| {{flag|Sweden}}
| [[Bofors]]
| 25x205mmR (initial) or 25x187mmR (later)
| Anti-aircraft autocannon
|}

==See also==
*[[14.5×114mm]]
*[[20 mm caliber]]
*[[23 mm caliber]]
*[[25 mm grenade]]
*[[30 mm caliber]]
*[[List of cartridges (weaponry), pistol and rifle]]

== Further reading ==
*U.S. Army Field Manual 3-22.1

==External links==
*[http://www.fas.org/man/dod-101/sys/land/25.htm Federation of American Scientists: 25mm Ammunition]
*[https://www.denix.osd.mil/denix/Public/Library/Explosives/UXOSafety/Photogallery/Small/smallmun.html UXO Safety Information]{{Dead link|date=April 2019 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Firearm cartridge calibers}}

[[Category:Large-caliber cartridges]]