TR2750, page 8 (1989)
ONE-SHOT MISSILE PACKS
It is possible for a vehicle or 'Mech to be equipped with a single-shot version of the standard missile launcher. Such a missile system is designated by an "OS" after the missile nomenclature.
Game Use
Single shot launchers weigh half a ton more than standard missile-launchers, but the launcher incorporates a single shot or volley of missiles into that weight. The player does not need to purchase any other ammunition for the launcher. The launcher can be fired only once in a game.
Single-shot launchers were voted the #1 most hated piece of BattleTech technology. They're dinosaurs, relics from the age of 500kg pintle mounts and 5-ton jeeps, used all of six (!) times since their introduction - I doubt most participants would've even remembered them if not for recent discussion or seeing other voters' ballots. So I have to believe that their spot at #1 doesn't represent
hate as much as amazement that Catalyst didn't bring them into line with the rest of the relaunch.
Paint-it-Pink: "
One-Shot Launchers (SRM, MRM, LRM) rules are a complete waste of time, so again not cool. My reading of the rocket launcher rules suggests that the fix is in, but the will to remove useless stuff is lacking. I can see from an RPG perspective that one-shot launchers may offer more in-character role-play opportunities, but for BattleTech the boardgame, not so much."
Centurion13: "No arguments here. I would expect such devices on vehicles, but not on a ‘Mech. Other than a drastic reduction in weight (and I don’t really see that), the only advantage would be to allow the use of special ammunition. And who wants a launcher that can only plant a single minefield?"
I figure they were originally meant more for scenario vehicles than for player or campaign vehicles. In 1989 it wasn't worth FASA's time to create a whole new detailed ruleset for very small weapons (probably figured individual GMs could handle that). But nowadays, Rocket Launchers are close to the weight of BattleArmor missile tubes, which means we should nearly
have a detailed ruleset for putting such small single-shot weapons on BattleMechs.
Or, we could leave the construction stats alone, and fiddle with other aspects. It's been said that BattleTech doesn't have any real surface-to-air or air-to-surface weaponry, and the ability to make such an attack at low atmosphere ranges (.5km hex ranges instead of waiting to get within 30m hex ranges) might be worth a few extra tons.
Another option is to increase damage. Doubling or quadrupling would bring them in line with Rocket Launchers, though 10x would be closer to what the regular reloadable models throw... a fivefold increase (5-point missiles for OS-LRMs and 10-point missiles for OS-SRMs) feels like a good comprise. Make each tube occupy its own vehicle slot so you don't have to worry about the ol' 60-ton missile carrier loosing hundreds of damage in a single turn.
Unbound has a "thunderbolt" missile (precursor to the
Tactical Handbook, Maximum Tech, and
Tactical Operations weapon of the same name). For 1 ton and 1 crit it was a one-shot weapon with the same stats as an AC/10, but you were limited to one per shoulder. (I'm going from memory, so those stats might be a little off. I would give the full text but I haven't got
S7, Unbound, or
The Reaches.)
And now, for the sake of making this post WAY longer than it needs to be, here's everything I can find on one-shot missile packs:
TR2750, page 96 (1989)
LIGHTNING
The Lightning's design gives it a limited but important combat role. Carrying only light armor and weaponry, the Lightning is not well-equipped to engage in protracted fire-fight. The craft's agility and advanced fire-control system allow it to close at high speed, maneuver to a position of advantage, and fire its small but accurate array of short-range weapnry.
In this way, the Lightning can harass enemy forces, especially slow 'Mechs and vehicles. Commanders often organize teams of Lightnings into strike forces, employing them in the initial phases to break up enemy formations and to cause general confusion.
When used for other missions the Lightning has many drawbacks. Not well-equipped to perform reconnaissance and too poorly armed and armored for more traditional combat, the Lightning can become a liability when its particular uses are unnecessary.
Hah, 1989 design philosophy: they didn't design the Lightning as a 35-ton hovertank with whatever weapons would fit on a 35-ton tank, they designed it as the kind of vehicle that you'd expect to carry one-shot missile racks (and the OS weight helps to keep it that way). This is the debut of OS-missiles, so it makes sense that they'd want an exemplar vehicle.
(It's also the only vehicle in the book to mount Pulse lasers which could be why it, like the
Sentinel, has a second targeting system.)
BattleTech Compendium, page 121 (1990):
SINGLE-SHOT MISSILE LAUNCHERS
The single-shot missile launcher can use special munitions, such as Swarm or Thunder LRM rounds, and special targeting devices (Streak, Narc, or Artemis), at double the base cost of the launcher. All other performance characteristics are the same as for multi-shot launchers of the same type and ordnance.
Slightly reworded name and description (I cut out the redundant bits, which I'll continue to do). Special munitions now apply their ammo cost multiplier (which happens to be "x2" for all of them so far) to the C-Bill cost of a OS launcher, which the chart on page 129 pegs at half of an equivalent multi-shot launcher. So adding a single shot of expensive ammo to a OS LRM-10, 15, 20, or SRM-4 or 6 costs more than adding a full ton of the same ammo to a regular launcher. Yippee? At least Inferno two-packs (inferno ammo costs half as much as regular ammo) become dirt cheap!
This writeup also omits the part about OS launchers massing an extra half-ton, but considering that no other book ever picked up on that (I'm not counting the
War Dog) and the rule isn't marked as significantly changed, I suspect the omission was accidental.
TR3050, page 148 (1990):
QUICKDRAW
What has created a furor is the substitution of a Hovertec Short Range Missile Detachable Quad for the old model mounted in the center torso. This one-shot weapon is normally used only on helicopters, hovercraft, and other vehicles designed to make a single offensive pass and then flee. The lack of reloads for the Detachable Quad seems too large a drawback to offset the safety gained by removing the ammo bins from the Quickdraw's center torso.
I can't decide if the SRM-4 (OS) is there because they wanted to use every kind of weapon once or if they simply wanted the
Quickdraw to have a flawed upgrade. The fact Technicron Manufacturing removed the SRM ammo entirely suggests that they were unable(!) to fit it in a side torso. Cool that the missile pack is detachable - I wonder if that was inspired by Elementals' missiles?
"ENGINEERS TESTS" includes a sentence on page 217-218 about OS launchers weighing an extra half ton, but the rule is otherwise identical to what's in the
Compendium.
Comstar SB, page 100 (1992):
RAIJIN
The Raijin mounts a one-shot Holly SRM pack in its center torso. Concealed from IR scanning by heavy insulation, this SRM rack is revealed by activating a swing-open mechanism, allowing MechWarriors to use this hidden weapon at close ranges to devastating effect.
More than a little surprised to see a one-shot weapon on a 'Mech where everything else is high-tech, though I suppose you could play off some of the OS' tonnage as IR shielding and other concealments. TR3058's writeup goes on to say that "Recent models of the
Raijin come equipped with a standard SRM-6 rack for more staying power."
Speaking of OS weapons and TR3058, the Peregrine Attack VTOL (and VTOLs in general) might reach more realistic weights and speeds if they were rebuilt with BattleSuit-esque weapons and armor.
TR3055, page 74 (1992):
WAR DOG
The War Dog carries a last-ditch weapons system in the two SRM Streak one-shot missile packs mounted on the upper legs of the 'Mech.
Ibid, page 97:
GRAND TITAN
As a last-resort weapon, the Titan also mounts two Holly Streak SRM packs, one-shot firing tubes mounted on the upper shoulders of the Titan near the "neck." Pilots often use these tubes for pointblank firing.
The
Kraken variants don't mention a OS launcher, but RS:3055 does, so I assume the record sheets added it as filler.
My book's
War Dog assigns 9 more armor points than it has (violating torso and arm limits), adds up to 70 tons instead of 75, and depicts its Streak-2s (1.5 instead of 2 tons each) on the lower instead of upper legs. "Leg mounted" usually means "hips" since legs move too much for aiming, but I suppose that calf-high works if you need to aim into places where infantry go, or if you really want to launch torpedoes in depth-0 water. And you're not likely to line that shot up more than once anyhow.
My book's
Grand Titan adds up to 100 tons (engine is misstated as 26.5 instead of 26.25 tons). The Streak-2s don't show up in the stat block, though one is drawn on the outside of each arm and two are shown in the 'Mech's "forehead" instead of its neck. It'd probably be easiest to implement BattleSuit-scale OS weapons on a 'Mech like this that doesn't actually devote tonnage to them in the first place.
I've heard that different printings list different (though still wrong) stats for these and other 'Mechs. It'd be fun to know just what!
Maximum Tech, page 90 (1997):
IMPROVED SINGLE-SHOT MISSILE LAUNCHERS
A Level 3 single-shot missile system weighs half a ton less than the launcher itself, including a single salvo of ammunition at no additional cost in weight, space or C-bills. These missile systems follow all other standard rules for single-shot launchers given on p. 120, BTC:RoW.
The beautiful thing about this rule is, in a time before BattleArmor construction rules, it let you build BattleArmor. Elemental = small laser (.5 ton) + 10 points clan ferro (.5 ton) + OS SRM-2 (0 tons) = 1 ton; Kanazuchi = medium laser (1 ton) + 15 points armor (~1 ton) + 2x OS SRM-2s (1 ton) = ~3 tons; and so on.
But everything that isn't a Clan SRM-2(OS) still weighs too much to put on 'Mechs or whatever else you're supposed to put them on, and Clan SRM-2(OS)s weigh too little to be used responsibly. Fill all your empty critical slots with free weapons that don't explode! Yay!
(I don't have
BattleTech Compendium: Rules of Warfare, but I assume it uses the same wording as
CityTech 2e (1994), whose page 71 rewords the rule from TR3050 and then tacks the half-ton sentence onto the end.)
BattleTech Master Rules, page 129:
Single-Shot Missile Launchers
Any type of missile weapon can be single-shot, including SRMs, MRMs, LRMs, Narc missile beacons and torpedos.
Arrow IV (OS), anyone?
This is a longer version of CityTech 2e's rule, and (though I'm not going to read anything into this) fails to mention special targeting systems (Artemis and Streak). It then goes on to explain that you multiply the cost of the launcher instead of the cost of the ammo "because ammo is not sold separately" - either the writer wanted to justify why a single shot of ammo costs so much (if so, he missed the point) or he was just rambling.
Field Manual Periphery, page 169 (2002):
ROCKET LAUNCHERS
At the same time, he directed his scientists to begin developing low-tech weapons that could be both readily mass-produced and easily retrofitted onto a 'Mech or tank.
The one and only major weapon system to survive initial field tests was one similar in concept to the Draconis Combine's recently developed MRM series of missile launchers. Instead of combining massive launcher racks with a complicated ammunition-feed system, the Hegemony's designers took a far simpler approach by making these new launchers completely self-contained, firing a single flight of unguided high-explosive rockets that are easily reloadable by hand in the field, making them nearly perfect for the still decidedly low-tech Marian legions. The main drawback was that the designers could not incorporate guidance packages into the rockets or the launchers without giving up too much space and mass.
So most of the weight in a BattleMech weapon is the ammo feed and, to a much lesser extent, the guidance and fire control (hey, weapon control helped push the
Commando from 20 to 25 tons!). It makes sense, you've got to draw shells or missiles or powerful electricity a couple meters through the 'Mech's torso, through the shoulder, and several meters back down to the forearm (if the weapon is in the torso with the ammo, then I guess the weight goes instead to aiming and radiation shielding).
I guess the real advantage of Rocket Launchers isn't that they're any easier to manufacture than LRMs or SRMs (by however much easier MRMs are), but that once your soldiers have the missiles, they aren't limited by your supply of LRM and SRM
launchers.
TechManual, page 230 (2007):
SINGLE-SHOT (OS) MISSILE LAUNCHERS
Introduced: 2676 (Terran Hegemony)
Extinct: 2800 (Inner Sphere)
Recovered: 3030 (Free Worlds League)
A variation on the LRM, MRM and SRM systems (including Streak launchers, torpedo launchers and even the Narc missile beacon launcher) the single-shot launcher--also known as one-shot or OS--is a curious concept that did not so much go extinct in the Succession Wars as fall into general disuse. Hardly considered lostech (even the date given for the first introduction is more to pin down when the use of one-shot launchers became common for the SLDF), the single-shot missile launcher design simply modifies a standard missile launch system with a shortened, fixed-mount ammo bin carrying a one-salvo capacity. Used only when tonnage is at a premium, one-shot launchers offer a little extra punch in a pitched fight, but with an all-or-nothing approach that can be as much a curse as the lack of a bin full of explosive munitions might be a blessing.
Of course, with the advent of the generally more potent Marian-style Rocket Launchers, the One-Shot missile concept may once more be on its way to extinction.
Ibid, page 261:
SINGLE-SHOT (OS) LAUNCHERS
Excepting rocket launchers--which gain this feature for free--a single-shot variation is available for most battlesuit-mounted missile launcher designs. Unlike the vehicular variety, which presents a slight mass increase due to the specialized small-scale ammo bin, the battlesuit single-shot system removes a typical missile launcher's ammunition feed mechanisms and bins in favor of individual, pre-chambered and launch-prepared warheads. This adaptation slightly increases the weapon's bulk, but presents a tonnage savings that makes up for--in some cases, anyway--the loss of battlefield weapon endurance.
Back 1989, stats were flexible in what they "really" represented in-universe (remember, 5-ton jeeps and 500kg pintle mounts). So maybe a OS-toting vehicle "really" massed less than its final tonnage, or the wasted mass represented lower grade manufacturing in the vehicle's other parts, or whatever.
In 2007, stats are taken to be accurate and exact depictions of the universe. TechManual describes the OS system as identical to a regular launcher, full ammo feed and everything, except that the ammo bin is occupied by other more urgent equipment. Either a) the factory will eventually issue a field kit to restore the ammo bin (I guess I could see the Star League building quick, temporary variants) or b) guys are hacking their machines up in the field (which would get more, not less, common in the Succession Wars).
...Now that I think about it, that factory explanation would actually work for the
Raijin, Grand Titan, and
War Dog. Neither works for the
Quickdraw or
Lightning, though I'm sure the QKD-5M is what they're thinking of with the FWL recovery date. (TR3050:Upgrades places a Streak SRM-4 (OS) on its
Daishi C, but I don't know where the fiction for that variant is.)(And while I'm on TR3050:Upgrades, it looks like, even though FASA discussed and depicted many "side" mounted weapons firing into their vehicles' forward arcs, Catalyst stuck a SRM-4(OS) sideways through the the Lightning's air intakes...)
Why do BattleSuits get any kind of discount for OS launchers? Ammo feeds can be measured in inches here, so
all the shots would be "launch-prepared," if not "pre-chambered." Count feed mass with each shot of ammo if you must.
PS, General
TechManual gripe: note that one section is titled "...missile launcher" and the other "...launcher." That's how the index lists them, one word difference and no sign which is Mech and which is BA, and meanwhile the equipment tables list both as "One-Shot" instead.
Tactical Operations, page 327 (2008):
IMPROVED ONE-SHOT (I-OS) MISSILE LAUNCHERS
Introduced: 3056 (Draconis Combine), 3058 (Clan Nova Cat)
One-shot missile launchers were always a quick-fix design, taking existing launchers and sealing off the ammunition feed mechanisms to contain a single, "unchambered" flight of missiles. Developed after the Clan Invasion in an effort to further streamline these weapons, DCMS engineers discovered how to do away with the ammo feed mechanisms entirely by placing the missiles directly in the launch tubes, a trick the Nova Cats would soon copy.
I've got tell ya, I'm pretty sure that ammo feeds -at least on most multi-ton weapons- mass more than half a ton. Also, "one-shot" missile launchers weren't always a quick-fix design (see: the first OS design ever published), but that type of missile carrier would be seen mostly with planetary militias or infantry, which BattleTech doesn't generally care about.