Actually, digging a bit deeper, I see I confused some things.

1) LBX weapons do two kinds of damage – direct and splash.
2) Splash damage is “chunked” so that it is always in hits of 2 or less; more overflows to new locations.
3) Each splash hit is a separate roll on the model, so it can hit anywhere.

Then we have one straight up code bug:
4) Splash damage for Light LBX is 0.5, which is accidentally coerced to 0.

The rest of the LBX family has integer splash damage, so they don’t hit that bug. Even according for that, the damage cards for all LBX aren’t right, but that could be changed via tuning cycle times, direct damage, or splash damage.

Gun family wise:
Light LBX: does 0.5 direct damage and 0 splash (should be 0.5, but the bug). Assuming no bug this is the same damage per strike as other light autocannons, but they have longer cycle times, so their DPS is worse. However, you do get roughly 2x the number of shots from the ammo, so the total damage dealt over a whole mission might be higher.

Medium LBX: does 2 direct damage and 2 splash, compared to 6 for other medium cannons. This is basically just worse, except again they have between 2x and 3x more ammo than their equivalents.

Heavy: does 5 direct and 6 splash, compared to 15 for the other heavy cannons. Again, much worse, except here we get 3x the ammo.

Assuming the splash bug is fixed:
1) Lights hit for 0.5, and splash for 0.5 on one segment
2) Medium hits for 2, and then splash for 2 on one segment.
3) Heavy hits for 6, and then splashes for 2 on three segments.

So this suggests:
Light LBX: ~30% dps loss (due to cycle time) and damage spread across 2 locations, but double ammo.
Medium LBX: ~33% dps loss (due to low damage) and damage spread across 2 locations, but double ammo
Heavy LBX: ~40% dps loss (mostly due to low damage, a little cycle time) and damage slightly more focused on the primary hit though still spread across 4 locations, but triple ammo.

So all the LBX guns do more damage than their non-LBX counterparts… once the non-LBX runs out of ammo and the LBX keeps going. It takes quite a while for that to even out.

Hm, it sounds plausible at a glance, but if direct damage into splash damage is how it works across the LB-X lineup then the test result shown for the Heavy LB-X test near the bottom of the OP doesn’t make sense to me (though maybe I’m just envisioning the damage calculation wrong in my head?). If even the Heavy seems to be dealing <33% of the non-LB-X damage then I don't think a rounding error accounts for the missing DPS - it still seems to be off by close to an order of magnitude when the Heavy non-LB-X punched to orange structure on the CT while the Heavy LB-X struggled to get past yellow armor anywhere. If the issue was rounding, then I'd expect it to not make much difference to total raw DPS for weapons with very high damage values.

1) LBX weapons do direct damage, and then a splash effect.
2) The splash damage for Light LBX is set as 0.5 per segment on 3 armor segments
3) 0.5 is accidentally coerced to 0 due to a small type conversion error

Medium/Heavy versions aren’t busted, but are a tad undertuned – given that focused damage is generally much better in Battletech, you really need a lot of extra damage to make them competitive.

(There may be a secondary effect reducing the splash damage further related to the time delay for explosions, but I’m not sure).

Well it’s written up now, so I guess you can decide what depth of magic I’ve had to do vs how much it is just explained by sitting down and testing how things work 😛

https://mhloppy.com/2026/05/mechcommander-weapons-left-arm-bug-fix/

Weapon placement thought was before I took a closer look ingame and noticed how wacky the effects are.

Loadouts, true. Battletech as a system always has been kind of prone to convergence when over-optimised though, usually on energy weapons and specifically the Clan ERPPC, ERLLaser and LPulse. Environment effects and the newer damage-type-resistant armour can affect that, as with combined arms; a Hellstar will eat mechs and tanks for breakfast, but can’t do anything to infantry. They have been tweaking the rules lately to even things a little but the need to keep statlines the same to avoid invalidating decades of unit designs means there’s only so much that can be done on tabletop rules.

Imo making small changes to the exe (when it has debugging symbols available like both MC1 and RoN do) is pretty low-hanging fruit in the grand scheme of modding, and the tools and some beginner-friendly tutorials for getting started have been around since at least 2020 or so. Since working on RoN patching I’ve been perpetually surprised by people’s generally near-complete unwillingness to engage in learning how to do it given how fantastic some of the learning materials that have come out are and how much power it gives you to change things.

Trying to replicate the position of stuff in the loadout feels a bit strange when the mech editor for the game doesn’t even support choosing component locations and the printouts for the mechs won’t tell you where things are, but god speed in your pursuit of flavor 😛

Thinking about it now, I kind of wish there was a (..well done) modern remake (or like.. SEQUEL!?) that allowed for a bit more depth in mech customization. Customizing and iterating on loadouts is one of the big appeals of the MW/MC (and HBS Battletech) games for me, but it’s so simplistic in MC1. I guess in a way it matches the relative simplicity of the combat though; there’s not much reason to try most of the loadouts because slapping XYZ weapons on a mech if you have them is just stronger lol. I think the only time I changed loadout strategies much is when I was defending a base with a known repair bay (switch to using more ammo-based weapons), but I otherwise just kept a mental list of like 10 weapons to choose between and barely touched the rest of them. The curse of player optimization I guess 😔 Edit: stuff like being pushed to switch loadouts based on mission environment would’ve been great too, like (if heat were modeled in game mechanics) hot/cold biomes, fighting enemies that use a lot of AMS, fighting areas with lots of terrain (bad LoS) etc so that there’s an actual reason to tweak the loadouts.

MW5:Mercs had a short-lived “MechCommander” mod that I would’ve definitely tried out if it was still being updated. Something like an official / more polished version of that I’d be pretty happy with.

The modder’s curse, seeing something not-quite-right and being compelled, like a vampire seeing a pile of loose change, to sort it out.

Before the update I was going to say that you may have been underestimating yourself given that what you had earlier was more progress than had been made on this in 30ish years. Shoulders of giants and modern tools etc but still.

Had been noodling a little but I suspect I’m generally a much slower operator; was thinking about something that would try to get as close as possible to the mech’s usual loadout distribution for consistency/flavour, but I’m not sure weapon location has anything to do with where the visual effects (muzzle flash, projectile etc) fire from. Probably in one of the unknown filetypes in Shapes, .hsp probably. But that’s just cosmetic.

Ah for fuck’s sake, I got a brain worm thinking about why the code I was looking at didn’t work, and every time I stopped working on it I just ended up coming back. Luckily for both of us, for the two weeks right before you left your comments I’d actually been doing some hardcore work on Rise of Nations and the time estimate I gave for how long it would take to fix assumed my level of skill from before my patching spree. Because I did that intensive patching work, I’ve actually gotten meaningfully better at a few things. Still not “fix it in a few hours” better, but 1 day instead of 1 week.

I’ve managed to undercover the cause and implement a patch (albeit a bit of a janky one) which correctly distributes “large” weapons across both arms and side torsos instead of just piling it all into the left arm. I’ll do a writeup about it later and leave RiZZen a note, but I was right in my initial assessment that it wasn’t that hard to fix. https://imgur.com/a/vlFGILI

Something interesting about this is that both of my pilots punched out / died after I blew off their left (?) arm. Based on that, this proof-of-concept change might have actually placed the engine or cockpit in their arm LOL.

Well, on a whim I took a stab at finding the game (exe) code that handles placing weapons, and I’m pretty sure I found it. After making a very blunt change, I seem to have placed all weapons in not-arms and sensors in whichever arm is the left arm on the paperdoll (I don’t remember if the paperdoll is mirrored): https://imgur.com/a/oopSVvA (the weapons lists are image edits so that the full lists can be seen)

I expect somebody with my level of competence could probably have a reasonable solution in a week or two of work, or someone more competent than me could do it in a couple of hours (my thing here isn’t a solution, just a test that I correctly identified the code).