LB-X Autocannon

LB-X Autocannon

The LB-X autocannon is an advanced variation of the standard autocannon. Its most notable feature was its ability to fire cluster munitions.

It remains unclear what "LB-X" actually stood for. Several suggested explanations are:

  • "LB" supposedly stands for "Lubalin Ballistics", the original designer and manufacturer of the weapon[1][2]
  • "Light Barrel - Extended Range"[3]
  • "Large Bore - Extended"[4]


Originally developed as part of the CROATOAN project in 2595 by Lubalin Ballistics for the Terran Hegemony, the LB-X 10 autocannon was a derivative of the standard and relatively primitive autocannon/10 design used for centuries by every military in the Inner Sphere. Taking advantage of advanced materials such as endo steel, the company was able to reduce the weight of the weapon with only a slight increase in bulk and mated it with the advanced Mercury-IV targeting system, to boost its effective range. The most notable feature of the weapon was its ability to fire both standard HEAP rounds and a specialized anti-'Mech cluster round.[5][6]

The cluster round fragments in flight, peppering the target with hundreds of explosive submunitions. The cannon is able to punch through an opponent's armor with standard rounds, and then fire cluster rounds to increase the chance of scoring a critical hit on a target's internal systems. The LB-X's flak-like "shotgun" effect also made it an effective and deadly weapon against aerospace fighters, VTOLs, and infantry.[5][6][7]

Rushed to the frontlines, the LB 10-X would first see service with the Star League Defense Force during the final battles against the Rim Worlds Republic and the Taurian Concordat during the Reunification War.[8] By 2680, all the Star League member states were manufacturing the popular weapon for their own needs and even for export to Periphery buyers. Because it was so successful in its role, the Star League ultimately chose to allow development to stagnate with the LB 10-X model.[6]

Like many pieces of advanced technology, the LB 10-X became LosTech in the Inner Sphere after 2840 during the maelstrom of the early Succession Wars. The Clans, however, retained the knowledge to produce the advanced materials the LB-X used, and had adapted and expanded the technology to produce LB-X versions of all autocannon classes around 2820.

Long noted for their affection for autocannons, thanks to the Helm Memory Core the Federated Suns regained the ability to produce the original LB-X 10 in 3035, and using this weapon and Clan-tech salvage were able to introduce Inner Sphere versions of the other LB-X classes in 3058.[7][9][10][3]

LB-X autocannons could not use the special munitions developed by the AFFS, and could not be combined with ultra, rotary, or light autocannon technology.[7]

The following subtypes of LB-X autocannon existed:




  • This article refers to a common object and addresses the object as a common noun. The preferred term is "LB-X autocannon" (except on section titles & table headings, where "LB-X autocannon" is favored). When addressed by class, the preferred term is "LB 5-X AC" (et al), with "autocannon" abbreviated to "AC".
That is a legacy of one of the very rare times where a weapon system was named by its brand, rather than as a generic. LB stands for Lubalin Ballistics, who made the LB-X weapons used in the Star League-era Champion BattleMechs.


Herbert A. Beas II

  — Herbert A. Beas II, Lead Developer, 24 March 2014


  1. Technical Readout: 2750, p. 34, "CHP-1N Champion
  2. Lead Developer confirms name meaning for "LB-X"
  3. 3.0 3.1 Era Report: 3062, pp. 104-105, "Museum Technica - Production Directed - LB-X autocannons"
  4. Über dem Gesetz
  5. 5.0 5.1 Technical Readout: 2750, p. 8, "LB 10-X Autocannon"
  6. 6.0 6.1 6.2 Era Report: 2750, p. 98, "Museum Technica - Offensive Military Technologies - LB-X Autocannon"
  7. 7.0 7.1 7.2 TechManual, p. 207, "LB-X Autocannon"
  8. Historical: Reunification War, p. 180, "LB 10-X (LB 10X-P)"
  9. Era Report: 3052, p. 100, "Museum Technica - Technological Renaissance - Ballistic Weapons"
  10. Era Report: 3052, p. 102, "Museum Technica - The Clan Edge - Ballistic Weapons"
  11. 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 Tactical Handbook, p.54