Ultra AC/20

Ultra Autocannon.jpg
Ultra AC/20
Production information
Type ballistic (rapid-fire)
Tech Base Clan / Inner Sphere (IS)
Year Availability Clan = 2825 (CSV)

IS = 3060 (LA)

Technical specifications
Heat Clan = 7/shot

IS = 8/shot

Damage Clan = 20/shot

IS = 20/shot

Minimum Range Clan = 0

IS = 0

Short Range Clan = 1-4

IS = 1-3

Medium Range Clan = 5-8

IS = 4-7

Long Range Clan = 9-12

IS = 8-10

Tons Clan = 12

IS = 15

Critical Slots Clan = 8

IS = 10

Ammo Per Ton Clan = 5

IS = 5

Cost (unloaded) Clan = 480,000 C-bills

IS = 480,000 C-bills

Ammo Cost (per ton) Clan = 20,000 C-bills

IS = 20,000 C-bills

BV (2.0) Clan = 335[1]
42 (Ammo)[1]

IS = 281[2]
35 (Ammo)[2]


The Ultra AC/20 (also UAC/20) was the largest bore Ultra autocannon. Like all Ultra autocannons, it was capable of twice the rate of fire of a standard autocannon, doubling its heat output and—potentially—its damage. Only the Clan HAG 40 could match the sheer damage output of the Ultra AC/20. The only weapons capable of delivering more damage to one location were the heavy Gauss rifle and the experimental improved heavy Gauss rifle.


In the years between the Second Exodus and the beginning of Operation KLONDIKE, the nascent Clans began development of what would become the Ultra AC/20. Experimental prototype versions of this new weapon were used during Operation KLONDIKE in small quantities. The Clan prototype Ultra AC/20 available during this period had identical stats to the Inner Sphere Ultra AC/20 required additional mounting space and was more prone to jamming.[3]


The Ultra AC/20 was used on the following planets in the Inner Sphere:

Aero-Model 4[edit]

Planet Manufactured by Typically used in References
Kirin Kirin Orbital Works SJ-3 Xerxes [4]

Ceres Huang Di[edit]

Planet Manufactured by Typically used in References
St. Ives Ceres Metals Industries Po [5]
Menke Ceres Metals Industries Po [5]

Defiance Thunder[edit]

Planet Manufactured by Typically used in References
Hesperus II Defiance Industries Blitzkrieg, Demolisher II, Hauptmann [6][7]


The Devastator was built to Clan specifications and had a caliber of 200 mm.[8]

Planet Manufactured by Typically used in References
Various Various Hunchback IIC [9]

Model SH[edit]

The Model SH Ultra Autocannon was built to Clan specifications.[10]

Planet Manufactured by Typically used in References
Sudeten Olivetti Weapons Bane (Kraken) [11]
Sudeten Tokasha MechWorks Alpha Bane (Kraken) [11]

Mydron Type 20[edit]

Manufactured on Manufactured by Typically used in References
Gulkana Yeffters Weapons Factory Centurion [12]

Type 10[edit]

The Type 10 was a 120 mm cannon.[13]

Planet Manufactured by Typically used in References
Luthien Luthien Armor Works SM1 Tank Destroyer [13]


  • This article refers to a common object and addresses the object as a common noun. The preferred term is "Ultra AC/20" or "UAC/20" (except on section titles & table headings, where "Ultra Autocannon/20" is favored).


  1. 1.0 1.1 TechManual, p. 318: "Clan Weapons and Equipment BV Table"
  2. 2.0 2.1 TechManual, p. 317: "Inner Sphere Weapons and Equipment BV Table"
  3. Historical: Operation Klondike, pp. 156–157: "Prototype Clan Systems"
  4. Technical Readout: 3067, p. 168
  5. 5.0 5.1 Technical Readout: 3085, p. 36
  6. Technical Readout: 3060, p. 30
  7. Technical Readout: 3060, p. 94
  8. The Price of Duty, ch. 8
  9. Technical Readout: Clan Invasion, p. 38
  10. Technical Readout: 3067, p. 126
  11. 11.0 11.1 Technical Readout: 3055, p. 122
  12. Technical Readout: 3058 Upgrade, p. 56
  13. 13.0 13.1 A Call to Arms, Prologue