My nitpick here is that the bombs are not actually 1 ton each... like a single arrow takes up 5 bomb slots, so 40kgper slot, while a RL10 takes up 1 slot but is a .5 ton item, ect. Bombs are what they are purely as a gameplay conceit for balanced gameplay. As for artillery, well artillery damage is comically too high. A 200kg AC20 does 20, but a long tom has that same shell size yet does 25 ae, 15 ae, 5 ae, for like 380 potential damage with 1 attack? Its a joke. Artillery is grossly overpowered, so comparing something like bombs which were balanced for gameplay isn't fair when artillery was buffed far beyond what is sensical.
Good catch. Is there a chart in a Core Book that lists the smaller masses for the different types of bombs? (I likely missed it)
The data I used was:
* Campaign Operations -> Maintenance, Salvage, Repair & Customization -> Design Quirks -> Internal Bomb Bay (page 227): each bomb slot used takes up 1 ton of cargo capacity
* Interstellar Operations -> Alternate Eras, Units & Equipment -> LAM Construction -> Bomb Bays (p114): "each of which weighs 1 ton and occupies 1 critical space in the unit’s left or right torso. Each bomb bay accommodates a single-slot bomb,"
* Tech Manual -> Heavy Weapon Ammunition Table (page 346) lists weight for various bombs as 1 ton each
You are right about the artillery damage though, I have similar comments about the Arrow IV vs the Thunderbolt-20:
| Weapon | Damage | Range | mass/shot | mass/lchr |
| Thunderbolt-20 | 20 | 18 hexes | 333 kg | 15 tons |
| Arrow IV | 20+ | 8 mapsheets | 200 kg | 15 tons |
Because ammo per ton is based on damage points - with the exception of AC/2s, and MGs (and Gauss) every ballistic weapon has 100 damage points per ton of ammunition - even the Artillery did, with the original, less absurd damage values (which the Cannon variants still use, despite nominally using the same ammo, hooray for plotholes); similarly with missile weapons (and gauss rifles) each ton of Ammo is equal to 120 points of damage.
Artillery is off because they massively buffed the damage but didn't apply a corresponding reduction in ammo counts; AC 2s are off because 5 rounds get shaved For Reasons; and MGs are off because their entire statline is wacky and seems like something added by someone who wasn't looking at the rest of the weapons at all. SRMs are off because, as far as I can tell, someone forgot that each missile does 2 damage and so didn't produce the correct ammo counts.
For MG, assuming the BT 3025-era standard Machine Gun is just the future version of the
M2 Browning 50 caliber machine gun, each bullet masses ~125 grams (from
here, but I increased the mass to make the math easy). 1 ton of ammo containing shots massing 125 grams per bullet is 8000 bullets. Assuming 400 shots this is 20 round bursts.
Now if the Battletech Machine Gun is a
20mm cannon, then each bullet would mass about
320 grams, so 1 ton of ammo would contain 3125 individual rounds. Assuming a 400 shots this would be a 7 or 8 round burst.
Now I'm wondering if all of the larger Autocannons need to be increased in shots per ton of ammo.
For SRMs and LRMs, I'd see them as a roughly similar platform, just that the LRM uses more of its mass for fuel instead of warhead. The LRM can burn the fuel, which reduces its mass during flight so the engine has less work to do over time.
The SRM however has to keep its 2-pt warhead on board for the entire flight. This is a warhead twice as heavy as the LRM warhead, imposing a constant and heavy penalty on range.
What would be interesting is changing missile internal explosion damage values to incorporate the missile fuel as well as the missile warhead. A simple method would be that all missiles do 4 pts of damage when they explode internally, to reflect the fuel + warhead doing damage. I would have gone with just 3 pts, but the Advanced Tactical Missile has a missile that does 3 pts of damage and still has the range of an SRM.
Or another option:
An LRM-20 launcher fires 1 salvos of missiles, and is lucky to get all 20 missiles to hit and do 20 pts of damage. The same LRM launcher later fires a Thunder-20 salvo, putting a 20-pt minefield into a hex. That 20-pt minefield has a chance to damage units wherever they walk in from, and only has a 50-50 chance to degrade (TO: AR, p176, General rules -> Minefields -> Conventional Minefields). How does the same tonnage of Thunder missiles get to damage units repeatedly when as LRMs they can only do up to 20 pts of damage?
My recommendation: Thunder LRMs only add 1-4 pts to a minefield, based on their missile strength divided by 5 (so that LRM-20 would only add 4 pts to a minefield hex).
