Monday, November 30, 2015

Rotary Firearms.

A monstrous device combining a ballet of mechanical precision and a ravenous appetite for ammunition and destruction, the rotary autocannon or "Minigun" is a Hollywood favorite for it's intense sound and light, as well as it's visceral effects.



Rotary Machineguns are heavy, mechanically complex, and typically mounted on a vehicle because of the vicious torque they generate and they eat vastly more ammunition in a single firefight than an infantryman (or possibly an entire squad) can reasonably carry. None of these considerations have stopped Hollywood from making rotary autocannons cinematic favorites though, and Cypher is nothing if not cinematic.


A weapon may have the "Rotary" property or the "Rapid Fire" property but not both. Rotary weapons may not be fired "Single Shot" for half-damage to conserve ammo, once the barrels start spinning it's all or nothing. (If a Rotary gun could be fired "Single Shot" the individual round would inflict 1/4 to 1/3rd base damage, or possibly less.) Rotary weapons may benefit from special abilities that require the "Rapid Fire" distinction, such as "Spray" or "Arc Spray".

Rotary weapons are massive, and count as one weapon size higher for purposes of weapon skills. IE: a Light Rotary weapon requires Practiced with Medium weapons to use without a penalty, Practiced with Light weapons imparts a 1-step attack penalty, and no weapon skill imparts a 2-step penalty. A Medium Rotary weapon requires Practiced with All weapons. Heavy, V-Heavy and S-Heavy weapons impart a 1-step penalty to attack for someone with Practiced with Heavy Weapons.

A Rotary weapon takes a few seconds to "Spin up". On the first turn a Rotary is fired the weapon inflicts normal damage, on the second and consecutive turns a Rotary inflicts double damage. First turn of firing consumes a full Attack of ammo as normal ("Attacks" worth of ammunition are an abstraction representing an "average" trigger pull rather than a specific amount of ammunition). Any turn that the weapon is not fired the barrels spin down and the next attack inflicts base damage.

A shooter may forgo the doubled damage to gain a one-step benefit to their attack roll by spraying the shot around rather than holding the weapon on the target. This benefit is neither a Skill Increase, nor an Asset and does not prevent any skill or Assets from being used.

Because of the weight of a Rotary's mechanics and the torque of the machinery that rotates the barrels the shooter must make a Might roll with a Difficulty of the base damage of the weapon (2 for Light, 4 for Medium, 6 for Heavy, 8 for X-Heavy, 10 for S-Heavy) or be Dazed for the next turn (increasing the difficulty of all rolls, including the second round of shooting, by one step).

If firing a X-Heavy Rotary weapon unbraced, the Might difficulty is 10. Other effects of firing X-Heavy and S-heavy weapons unbraced are cumulative with Rotary penalties. See Firearms in Cypher System for more details on X-Heavy and S-Heavy firearms.

Rotary guns and Swarms:

If you're ruling that an attack against a Swarm of creatures can only kill one creature at a time and excess damage is lost, Rotary weapons may spread their damage across multiple creatures in the swarm so that excess damage transfers to the next creature in the Swarm. (Shotguns firing Shotshell or Flechette rounds also benefit from this effect).

Feeding the Beast, Rotary Guns and Ammunition:

If you're using basic ammunition rules and counting individual bullets rather than "Attacks" Rotary weapons consume around 300 rounds per turn of firing (assuming a 6-second turn, at an optimal 3,000 rounds per minute).

If you're using the "Tons of Ammo" rules (Firearms in Cypher System) you might be looking at actual Tons of Ammo. Each time the party sets out on an adventure/mission they will need to acquire ammunition for each of their Rotary weapons. Each supply of Rotary gun ammo is treated as an Artifact with a Depletion of 1-2 of 6. Roll at the beginning of the game session where the Rotary was used in the *previous* session (if they didn't use the Rotary last session then they're not going to magically be low on ammo unless there's a GM Intrusion explaining why the ammunition went missing). When the depletion happens the Rotary can be used in one more game session and then it's out. (so if Depletion happens and the Rotary isn't used in that session then there's still one more game session of Rotary Ammo in the box).

Light Rotary ammo for one mission is a Moderately Priced item ($200)
Medium Rotary ammo is an Expensive item ($2,000)
Heavy Rotary ammo is a Very Expensive item ($20,000)
Very-Heavy Rotary ammo is an Exorbitant item ($200,000)
Super-Heavy Rotary Ammo is a Very Exorbitant item ($2,000,000)

These are large crates of Ammunition that require two characters to carry, and tend to be left back in the party's main transport rather than carried in to combat.

Optional: Carrying Rotary Ammo

Rotary ammunition is heavy and bulky, there's not only the extensive quantities of ammunition itself but disintegrating link belts and/or canisters adding to the weight. Each character can only carry one reload for a Rotary gun (the shooter may have two, one "in the gun" another on his person), and when the Rotary is out of ammo the character carrying the reload and the Rotary Gunner must be in Immediate range of each other to reload the gun.

It may be possible to attach two belts of ammunition together, doubling the number of attacks a belt-fed weapon can make before needing to be reloaded. A Double Length Belt inflicts a 1-step penalty to all movement tasks until the first belt has been consumed. This may be an option for any belt-fed machinegun, not just rotary autocannons.

(In the World Wars (1900-1950) ammunition belts were often made of fabric rather than the modern disintegrating link belts. A Double Length Belt of this type continues to inflict the penalty to movement tasks until the entire belt has been consumed).

Vehicular Rotary Weapons:

Rotary weapons mounted to a vehicle (like the 20mm or 30mm autocannons on most modern fighters) are only a special effect and have no special rules. They don't suffer from the weight or torque of the Rotary mechanism, and the increased damage from firing a Rotary gun is covered under the "Size Class" increase to the weapon's damage for it's class. A mounted weapon is assumed to be designed as an integral part of the vehicle with sufficient ammunition for the vehicle's mission profile.

If a Giant Robot were to be equipped with a scaled up Rotary cannon, or a vehicle were to be reverse-engineered with a rotary autocannon it wasn't designed to mount then the Rotary Gun rules above would apply as the weapon is not integral to the vehicle it is fired from. Damage on the second turn is the weapons base damage, doubled, then the scale modifier is added. The pilot or gunner still needs to make the Might roll from the vehicle's Might pool to avoid the crew being Dazed as the Rotary cannon attempts to vibrate the vehicle to pieces.

EX: a Size 3 Mobile Armor is equipped with a Medium Rotary weapon. The first turn the Mobile Armor inflicts 7 damage (4 base, + 3 size mod), the second and subsequent turns it inflicts 11 damage (8 for the doubled base damage, + 3 size mod). The pilot must make Might 4 rolls based on the mecha's Might Pool or be Dazed on the next turn.


Sample "Man Portable" Rotary Guns:

General Electric M134 "Minigun", 7.62 x 51 (Exorbitant):
A 6-barrel rotary machinegun used by helicopter gunners in the Vietnam war. The Russian GShG-7.62 and Chinese Hua Qing Minigun are similar designs. The M134 and the GShG-7.62 are primarily for aircraft deployment, however the Hua Qing has been purpose developed as an infantry/anti-terrorist weapon.
In the movie Predator "Blaine"(Jessie Ventura) carries a GE M134 Minigun with a custom (Hollywood) modification to allow it to be handheld. It's rate-of-fire was cut in half so the spinning barrels would be visible on camera instead of a blur, and the ammo feed only carried 4 seconds of "blank" ammunition.
Mythbusters used a M134 mounted on a SUV in a concealed pop-turret for the "Shooting Fish in a Barrel" and "Cutting down a tree with a machinegun" myths.
-Heavy Rotary, Damage 6/12, 10 attacks, Long Range, Rotary (Very Expensive)

GE XM214 "Microgun", 5.56 x 45 (Very Expensive):
The "Microgun" was developed in 1966 as a lighter alternative to the M134 using the smaller caliber 5.56 rifle ammo. Tests proved the smaller ammunition used by the XM214 to be unsuitable for use from aircraft (the rounds lacked the mass to resist airflow effects around the aircraft). GE redesigned the XM214 in to an 81-pound infantry-carried weapon system known as the GE 6-Pak, however the U.S. Army showed no interest. The weapon was part of their catalog until the late 1990's
-Medium Rotary, Damage 4/8, 10 attacks, Long Range, Rotary

Bonus Gear: Articulated Weapon Harness

An Expensive piece of gear, an Articulated Weapon Harness is a harness with an articulated arm with hydraulic pistons that help manage the weight and recoil of weapons that may cause the Shooter to be Dazed, like unbraced X-Heavy firearms and Rotary weapons. Using an Articulated Weapon Harness halves the difficulty of the Might roll to avoid being Dazed on the next turn.

A Sci-Fi "Robotic" weapon harness is a Very Expensive piece of gear that provides one Asset to the Might roll to avoid becoming Dazed in addition to halving the difficulty.