Okay, this is a really old topic, but I just finished data-mining
ER:2750's Museum Technica section. Only major manufacturers are explicitly called out in the text, but there's a lot you can read between the lines. If TPTBs are trying to make us realise the heights the Star League enjoyed before their precipitous plunge during the 'Mad Max' phase of the Succession Wars, they're doing a pretty good job, IMO.
Hell, they've done such a good job that it's actually put a couple of holes in some of my plans for the wider aspects of the Virginia War, but doing that hasty patchwork is actually kind'a fun in itself....
ERLL: “The ER large laser was widely produced across known space during the Star League. One of the major producers was Lushannâ€
> FWL (Diverse Optics), Outworlds (Lushann Industrials Ltd.)
Pulse Lasers: “The complex nature of the interlinking capacitors and control circuitry limited production to corporations with the most advanced laser production facilities. Beyond Terra, these manufacturers included:â€
> FS (Precision Weaponry/Tancredi IV), FWL (Diverse Optics), Outworlds (Lushann Industrials Ltd.)
Gauss Rifle: “The zero-gravity production techniques for making the superconducting coils limited the corporations and realms that could easily produce the Gauss rifle, but ground based manufacture of the weapon system was feasible. A dozen manufacturers across the Terran system, as well as Yankee Weapons systems of New Earth, produced the Gauss rifle for the SLDF. Across the rest of the Inner Sphere, Norse-Storm Technologies of Loxley, and Johnson Industries of New Syrtis were other major manufacturers.â€
> FS (Johnson Industries/New Syrtis), LC (Norse-Storm Technologies/Loxley)
LB-10X: “By 2680, the LB 10-X was being built in every Star League member state. The major non-Terran producers ... produced limited numbers of these weapons for export even to the Periphery statesâ€
> FS (Mydron Corporation), FWL (Oriente Weapon Works)
UAC/5: “The perceived failure of this weapon system made security around its design lax, and it quickly spread across the Inner Sphere and Periphery. Major non-Terran producers of the UAC/5 included General Motors of Kathil and Arc-Royal, Armstrong Weapons of Sterope and Dunianshire, and Imperator Automatic Weapons of Atreus.â€
> FS (General Motors/Kathil), FWL (Imperator Automatic Weapons/Atreus), LC (General Motors/Arc-Royal), MoC (Armstrong Weapons/Dunianshire), TC (Armstrong Weapons/Sterope)
AMS: “... the ease at which the old Phalanx idea was modified allowed the rest of the major powers of the Inner Sphere to quickly develop their own models. By 2750, the major producers of the AMS system included Blankenburg Technologies of Terra, Cal-Boeing in the Federated Suns, and Earthwerks, Inc of the Capellan Confederation.â€
> CC (EarthWerks Inc.), FS (Cal-Boeing)
SSRM: “The Holly Streak system was one of the most widespread brands in use ... the technology spread to the Federated Suns, Free Worlds League, and the Magistracy of Canopus. The second most popular brand of Streak launchers came from Hovertec, who produced these weapons for the Capellan Confederation, Free Worlds League, and the Lyran Commonwealth’s Federation of Skye.â€
> CC (Hovertec), FS (Holly), FWL (Holly, Hovertec), LC (Hovertec/Skye), MoC (Holly)
BAP: “The primary manufacturer, Clear Sight, Inc. of Luna, was able to keep up with all purchases from the HAF, while minor manufacturers across the Inner Sphere — such as Imstar Aerospace and Diplan Electronics — fulfilled the demands from the Great Houses.â€
CASE: “The complex network of cells and the construction of the diamond-fiber material for CASE limited the production of the equipment outside of the Terran Hegemony.â€
(Personally, I call BULLSHIT on this one, but that's just me)
DHS: “The ease with which the double heat sink can be built ensured that even the poorest Periphery world had the ability to produce it for its armed forces so long as the endo-steel frame for the heat sink was available.â€
ES: “... as late as 2750, the majority of all endo-steel production remained in Terra’s asteroid belt, and was used almost exclusively by the SLDF. Minor manufacturers in all of the Great Houses nevertheless struggled to keep up with demand, including Buckboard Ltd. of the Free Worlds League, and Tunguska Industries of the Draconis Combine.â€
> DC (Tunguska Industries), FWL (Buckboard Ltd.)
FFA: “As of 2750, few manufacturers outside of the Terran Hegemony had the complex and highly advanced production facilities needed to integrate diamond fiber into steel without the diamond dissolving into less effective carbides. The primary producers were Krupp Armament Works in the Terra system, Corean Enterprises of New Avalon (which produced the StarGuard brand ferro-fibrous under a Hegemony license), and Hellespont ’Mech Works of the Capellan Confederation.â€
> CC (Hellespont Mech Works), FS (Corean Enterprises/New Avalon)
GECM: “The Guardian ECM Suite found its way out of the Terran Hegemony before the end of the Star League. What frustrated the Great Houses and the Periphery nations was that the highly adaptable software needed to operate the Guardian required constant patching and custom recoding for each model of BattleMech it was installed in. The massive computer complexes available to the Terran Hegemony made this a trivial issue, but for the rest of the Inner Sphere it was time consuming.â€
TAG: “TAG, while complex, was fairly straightforward to produce and install on both vehicles and BattleMechs, though it was rarely seen due to the scarcity of TAG-enabled munitions.â€
XLFE: “Covert operations from all the Great Houses were able to obtain XL engine technology by the end of the twenty-sixth century.â€