BattleTech 3025: Weapon Balance
I started playing BattleTech with some university friends in the early 1990s, primarily using the 1990 BattleTech Compendium ruleset. The Clans had been introduced by this point, but we mostly played 3025.
Background
I played with two friends from the university wargaming club every Monday night for many years, plus occasional games in other contexts. A typical night was lance-on-lance, usually by tonnage. We often mixed it up with terrain and scenarios, and occasionally with artillery, non-mech units, minefields, and various other rules from the 3rd edition rulebook. Mech choices ranged from purely published mechs, published mechs with minor modifications, to entirely custom lances.
I still regard the 3025 technology rules as the “best” implementation of the ruleset. With 3025 tech and standard 4/5 pilots, everything was about tradeoffs. Even with custom mechs, you could never max out the speed / defense / offence triangle in all dimensions.
Weapons As Published
The focus of this article is 3025 weapons, so I’ll leave my general opinions on mech design for another day.
Rather than classify the weapons by type, I will start by classifying them by range bracket.
Close Range: 3/6/9
3025 BattleTech is optimised around range 3 and range 6. The most overall efficient weapon - the Medium Laser - and dangerous weapon - the AC/20 - both use the 3/6/9 range bracket. With good use of terrain and tactics, it’s usually possible to force enemy frontline mechs within 6 hexes.
Medium Laser
This is the baseline BattleTech weapon. 1 ton of weapon, 3 heat, 1 critical slot, 3/6/9, 5 damage. Fully sunk, this is 1.25 points of damage at the standard 3/6/9 range bracket.
AC/20
14 tons of weapon, 7 heat, 10 crit slots, and only 5 shots per ton of ammo. But each shot is 20 points to a single location. For the AC/20, 2 tons of ammo is just tolerable for lance vs lance, but this will discourage shooting at poor odds in the hope of a lucky hit. This still leaves 23 tons for 20 points, or just under 1 damage per ton.
In contrast, 24 tons could mount 6 medium lasers for a potential of 30 points.
The AC/20 is marginally more slot efficient that the medium laser: 10 (weapon) + 7 (sinks) + 3 (ammo) is 20 crit slots, vs 24 for the same tonnage of laser.
Short Range Missiles (SRMs)
The opposite of the AC/20. Rather than provide a single big hit, these instead deliver lots of little hits. Very useful if you’re trying to score critical chances or a lucky head hit, but not so much for punching a hole in a single hit location.
The SRM-2 is 1 ton, 2 heat, 1 crit, with a mean damage of 2.84 for 3 tons. The SRM-4 is 2 tons, 3 heat, 1 crit, with a mean damage of 5.28 for 5 tons. The SRM-6 is 3 tons, 4 heat, 2 crit, with a mean damage of 8 for 7 tons.
A strange quirk is that SRM-6 ammo is less efficient than ammo for SRM-4 or SRM-2 launchers: 15 shots (90 missiles) per ton vs 25 / 50 shots (100 missiles) per ton. We could get away with 10 shots per launcher (2 tons for 3 launchers for the SRM-6), but it’s easiest to assume 1 ton per launcher. Even so, the SRM-6 is the best value, with 8 damage for 8 tons vs 5.28 damage for 5.5 tons per launcher for a pair of SRM-4s.
Very Short Range: 1/2/3
These weapons have range 1/2/3. On paper, they offer an excellent damage to weight ratio. In practice, it’s not excellent enough to compensate for the difficulty of keeping an unwilling enemy at range 1.
The low per-hit yield of these weapons gives them a similar advantage / drawback as to SRMs - good for dealing crits, bad for punching through armour.
Small Laser
Half a ton, 1 heat, 3 damage. Nominal efficiency of 2 damage per ton comfortably exceeds the medium laser, but good luck trying to apply it.
Machine Gun
Half a ton, NO heat, and 2 damage. That looks even better than the small laser, but there’s a catch - you need to carry at least half a ton of ammo. There are some very unusual designs that are packed to the gills with machine guns, but most pilots will ditch most or all of their MG ammo as soon as they confirm that there are no infantry around.
Flamer
1 ton, 3 heat, 2 damage. As written, totally useless as an anti-mech weapon; over twice the tonnage of the Small Laser but less damage.
The optional rule that can convert the 2 physical damage into 2 heat damage is still somewhat bizarre - firing the flamer does 2 heat to the defender but 3 to the attacker. Possibly useful in a gimmick build, but still requires you to dedicate a huge tonnage to heat sinks in the hope of getting close enough to inflict some heat damage on an opposing mech.
Middle Range: 5/10/15 or 6/12/18
Each of range 5/10/15 and 6/12/18 has an energy weapon and an autocannon. The 6/12/18 range bracket weapons also have a 3 hex minimum range.
On many maps, getting a clear shot greater than 12 hexes is rare.
Large Laser
5 tons, 8 damage, 8 heat, 5/10/15. 13 tons for 8 damage is 0.61 damage per ton. This is less than half of what a Medium Laser can dish out.
AC/10
Matching up with the Large Laser is the AC/10. Only slightly lighter than the AC/20 (12 tons vs 14) it generates a lot less heat (3 vs 7) and gets twice as many rounds per ton of ammo. With a single ton of ammo it is 16 tons for 10 damage or 0.625 damage per ton.
On a pure damage per ton comparison the AC/10 matches the Large Laser only if you are willing to run with minimal ammo. Dealing 10 rather than 8 damage provides one other advantage - a hit to the head is guaranteed to go internal.
PPC
Everyone’s favourite mid-range weapon, and for good reason. 7 tons, 10 damage, 10 heat, 6/12/18 (min 3). At 0.59 damage per ton, it’s not immediately obvious why the PPC is so much more favoured than the Large Laser. In practice, that one extra hex of short range and two of medium range makes a huge difference.
Even in ideal conditions, a 5/8 mech cannot walk (and 3/5 mech cannot run) from outside short range into melee range
A short range of 6 means that a Medium Laser (or AC/20 or SRM) equipped mech cannot force both mechs into medium range. Pushing the PPC to medium range requires that the short-ranged attacker accept long range, which is almost always a bad trade.
For a very small damage drop over the Large Laser, the PPC equipped mech gains significant stand-off capability.
Like the AC/10, 10 points can go internal on a head hit.
AC/5
The best thing that can be said about the AC/5 is that there is at least one weapon even worse. 8 tons, 1 heat, 5 damage, 6/12/18 (min 3), 20 rounds per ton of ammo. At a pinch, we might go for share a ton of ammo between a pair of AC/5 mounts, but that is still 9.5 tons for only 5 damage, or 0.53 damage per ton.
Long Range: 7/14/21 and up
Long Range Missiles (LRMs)
The longest ranged effective weapon in 3025. Like the SRM, the LRM comes in various sizes. Rather than a small number of 2 point missiles, the LRM fires a larger number of 1 point missiles. LRMs have an interesting additional rule in that their damage is combined into 5 point clusters, even from multiple launchers. This gives them a damage profile very similar to that of medium lasers.
LRMs come in 5, 10, 15 and 20 missile versions. Except for the LRM-10, all variants require 4 tons per 5 missiles (2 tons & 2 heat for the LRM-5; 7 tons & 5 heat for the LRM-15; 10 tons & 6 heat for the LRM-20). The poor LRM-10 requires 4 tons and 5 heat which is 9 tons for its 10 missiles.
The missile damage tables are also subtly different for each launcher. All launchers use the same ratio for 5 and above, but the values for 2-4 differ. As such, the LRM-5 and LRM-15 deal expected 3.167 damage per 5 missiles, the LRM-20 3.174, and the LRM-10 again loses with 3.153.
Using the LRM-20 with a mere 2 tons of ammo as a baseline gives 12.7 damage per 18 tons, or 0.71 damage per ton. A more flexible 3 tons still gives 12.7 damage per 19 tons, or 0.67 damage per ton. This is notably superior to the medium range weapon systems.
LRMs have two other unique features, one a small drawback and the other a massive advantage.
LRMs have the longest minimum range in the game, 6 hexes. Only when firing at a target exactly 7 hexes away can a LRM fire without a range penalty. So most LRM fire occurs at medium range, or even longer.
As mentioned above, it’s hard to get a clear shot at over 12 or so hexes. LRMs come with another key feature - indirect fire. For a +1 hit penalty the LRM launcher can use a different friendly unit to provide line-of-sight. It can be very effective to park an LRM boat close to the action but out of direct fire, and essentially “loan” its LRM launchers to a friendly scout unit.
AC/2
What’s even less useful than an AC/5? An AC/2! For 6 tons and 1 heat you can hit like a machine gun or single SRM at 8/16/24 hexes. With half a ton of ammo per gun you are spending 7.5 tons to deal 2 points of damage, or 0.27 damage per ton.
Autocannon/2s have some value on fixed gun emplacement buildings, where they can be positioned to have a clear field of fire to extreme ranges, but it’s hard to tell what FASA was thinking when they specified them for BattleMechs.
Additional Factors
Baseline Comparison
Based purely on the tonnage numbers, energy weapons dominate. Except for LRMs, which are generally good, energy weapons have better damage per ton values than comparable ballistic or missile weapons even when those weapons carry a minimal ammunition load.
The AC/20 and SRM-6 squeeze in as honourable mentions; the AC/20 for its fear value and the SRM-6 for its crit-dealing ability. In both cases, you pay for this benefit with reduced base damage. In addition, the fear value of the AC/20 diminishes as tonnage goes up; unless the attacker gets a lucky head hit, most heavy and assault mechs can comfortably absorb 20 points of damage to any given location. When heavy mechs brawl, the extra damage from 6 medium lasers will usually tell out over the point damage of an AC/20.
Having a Victor land in your rear arc is still scary.
Hidden Benefits
But the energy weapon advantage doesn’t stop there. Energy weapons usually have less weapon tonnage and more heat compared to comparable ballistic or missile weapons. Heat means heat sinks, and all mechs get 10 heat sinks for free. In addition, a certain fraction of the heat sinks are mounted “in the engine” and don’t require critical slots.
In the first instance, this can mean that some lighter mechs can fit a PPC but cannot fit an AC/10. To fit the PPC only requires 7-10 tons, the rest of the weight being paid in “free” heat sinks. In contrast, the AC/10 requires at least 13 raw tons (12 for the weapon, 1 for the ammo) with only the 3 heat sinks being “free”.
This disadvantage reduces with larger mechs as it becomes more likely that they can consume all 10 free heat sinks.
Having more “space” in heat sinks also makes energy weapons more robust. Again, consider an AC/10 (16 total tons) and a PPC (17 total tons). The AC/10 requires 7 crit slots for the weapon, 1 for the ammo bin, and 3 for the sinks (total 14). The PPC requires 10 crit slots for the sinks but only 3 for the weapon (total 13).
Despite being a ton heavier, the PPC requires one less crit slot. In addition, only 3 of those 13 crit slots will disable the PPC. In contrast, a critical hit to any 7 of the AC/10 crit slots will take out the autocannon itself and a critical to the ammo bin might take out the mech.
Similar logic applies to all energy vs ammunition based weapons. Critical hits to heat sinks apply marginal damage; critical hits to weapons knock out entire weapon systems.
We’re not done yet! Energy weapons have three further benefits.
Because they are not ammo bound, they retain full effectiveness in long or large battles. In contrast, an ammo loadout that will suffice for a lance vs lance battle is often insufficient for a larger encounter, or if the battle turns into long range sniping.
Heatsink damage is fungible! If a mech has a mixed weapon load and loses a heatsink, it can choose which weapon to refrain from firing in order to manage heat. Or it can limit movement. Or it can fire anyway and accept additional heat gain. In contrast, a weapon crit disables that weapon.
More heatsinks = more flexibility. A mech with more heatsinks can recover more quickly from overheating, and retains more functionality in the case of an engine hit. For example, an Awesome (28 heat sinks) that overheats can clear any amount of heat in a single round of no firing, or even reduced firing, and can manage even 2 engine criticals by reducing the number of PPCs it uses each round. In contrast, an Archer (10 heat sinks) that overheats has a much harder time clearing its heat, and the only way an Archer with 2 engine critical hits can clear heat is to shutdown; doing anything other than standing still will make it run hotter.
Based on all the above factors, we would expect ammunition based weapons to be significantly more effective on raw numbers, with energy weapons catching up in flexibility. Instead, lasers and PPCs start out ahead of everything other than LRMs, and are more flexible as well.
Ultimate Brawler Combination
In addition to all the above, the PPC has another benefit that lifts it head and shoulders above all the other medium range weapons.
Consider a standard PPC setup: for 17 tons, you get a PPC and 10 heat sinks, for 0.59 damage per ton. This is effective from 4 hexes, though within 3 hexes is easily outperformed by medium lasers and other short-range weapons.
Now consider the following: PPC, 10 heat sinks, 3 Medium Lasers. This weighs 20 tons.
From 3 hexes, we fire the Medium Lasers. This is 15 damage for 20 tons, or 0.75 damage per ton. Not amazing, but better than any of the medium range weapons, and we avoid the minimum range penalty.
From 4-6 hexes, we have a choice: 3 Medium Lasers at +2, or 1 PPC at +0. If we use the PPC, we are still at 0.5 damage per ton, which isn’t bad.
Above 6 hexes we obviously fire the PPC.
In and of itself, that is still maybe not convincing. If you are committed to staying at medium range, why not skip the Medium Lasers and save the 3 tons?
The trick is that you have gained two additional tactical options.
Firstly, against another mid-range mech you can push forward into short range and get a damage advantage.
Secondly, you can burn some heat for a 25 point alpha-strike. Assuming you’re otherwise heat-stable you suffer a -2 movement and +1 hit penalty on the following round, but if you dealt enough damage this round that might not even matter.
To me, this combination is something of a “gold standard”. Any weapon needs to be compared against this.
Conclusion
I was going to discuss the modifications my group made to the 3025 weapons to give each weapon system a unique and interesting role, but this post is already too long, so that will have to wait for next time.