Shooting Transhuman Space Weapons

In GURPS, firing a gun is an Attack, All-Out Attack or Move and Attack manoeuvre. This may or may not be preceded by one or more seconds of Aim manoeuvre.
In Transhuman Space, we have the added complication that smart ammunition, including homing bullets, are relatively commonplace.
Any firing in non-homing mode will simply be called “Shooting” in the following passages. “Shooting” includes firing beam weapons, firing “dumb” ammunition and firing smart ammunition in a non-homing mode.
Shooting rules for GURPs are spread across several volumes. At the minimum, you need both volumes of the Basic Set and High-Tech. THS: Changing Times and Tactical Shooting are also desirable, and Gun-Fu and Ultra-Tech can be useful.
Even with all of these, how the rules are specifically applied to Transhuman Space may not be clear.
Many weapons in Transhuman Space cannot use smart ammunition. These range from zip guns and shoukwans to relatively sophisticated weapons like the Xuan Feng and laser weapons.
The following three firing modes apply to these and to smart ammunition used in “dumb” mode.
TL9+ personal weapons usually have HUD and laser sights fitted as standard.

Shooting without Deliberate Aim

Shooting without using the sights is a Move and Attack or Attack manoeuvre, never an All-Out Attack. There can be no Aim manoeuvre before.
Since such shots do not require seeing the sights. -1 in darkness penalties can be ignored at ranges up to Perception (Per) in yards.
A targeting laser provides a +1 modifier. Other targeting aids including HUD links give no bonus to unsighted shooting.
Items such as goggles, dive masks, gasmasks etc give -1 modifier to unsighted shooting.
Items such as VR/AR visors and spectacles give no modifiers since many THS-era citizens wear them daily so are very familiar with them.

Shooting with the Sights

Shooting using the sights is an All-Out Attack, so +1 to Guns, Gunner or Beam Weapon skill.
Goggles, dive masks etc give -4 to shooting using the sights.
You need to be able to see the sights so darkness penalties apply. A HUD-link or Improved Visibility Sights negate -1 of darkness penalties.
The GM may allow that a HUD-link acts like a micro-reflex sight, so gives +1 to Guns up to 50 yards (Cannot be taken with Laser Sight Modifier Tactical Shooting 4e p.74). Some HUD-links perform at even longer ranges.

Deliberate Aim

Deliberately aimed shooting is represented by an Aim followed by All-Out Attack.
The bonus for Aim usually only applies to the next Attack (p.B372).
The GM may allow shooters to retain half their weapon’s base Acc (round down) on subsequent sighted shots against the same target after using aimed shooting.
Shooters with braced weapons may add full base Acc when firing at RoF 1.
Mounted weapons on flexible or fixed mounts may add full base Acc even when firing at a higher RoF.

Homing Ammunition

In addition to the shooting modes described already, some weapons in Transhuman Space have a fourth mode of shooting using their homing ammunition.
The basic rules (p.B413) tell us that to be used as a homer, a projectile must be aimed first.
Unlike a usual Aim manoeuvre, this requires a success roll be made.
Basic rules state that during the Aim manoeuvre, the shooter must successfully roll against Artillery (Guided Missile) skill.
Transhuman Space: Changing Times (p.64) tells us to make this roll with the appropriate Guns or Gunner skill instead.
For clarity. I will call the Aim manoeuvre with a success roll, an “Aim and Lock”.
If the Aim and Lock is successful, the projectile(s) are fired with a Ready manoeuvre.
The attack roll is made by the projectile(s) when they reach the target, which may be the same turn. or in subsequent turns.
Changing Times tells us that the projectile(s)’ Attack is Homing (Vision).
Optionally, a Critical Failure in the Aim and Lock roll negates any Aim bonuses (A5) for the following shot.
Homing (Vision) implies that projectiles have night vision no better than an average human. Technological devices and biomods mean that many shooters in THS will often see their targets much better than their bullets!
The GM may allow that high quality, military or police-issued ammunition have some level of Night Vision. This will be more common in calibres in wide scale military use. 5.6mm, 6.6mm, 7.5mm and 10mm rounds may have Night Vision 4.
The tiny 4mm rounds only have Night Vision 2.
Larger calibre missiles may have even better Night Vision, depending on role and cost. Some will have multi-spectral capabilities.
Budget homing ammunition or that from dubious sources may have no Night Vision.
What is not made clear in the sourcebooks is which, if any, modifiers apply to the Aim and Lock and the Homing Attack rolls.
Logically, locking onto a distant, fast target would be more difficult than on a larger, closer target.
If you are on fire, this may or may not distract you from carefully aiming. If you are a cybershell or wearing an armoured powersuit, you might ignore a little bit of fire!
Rather than giving rules for every possibility and variation of circumstance, the GM should be logical and waive modifiers that do not apply.
Another question that arises is what happens if you fail an Aim and Lock?
The original THS sourcebook and THS: Changing Times both make it clear that homing bullets and other projectiles may be fired without an Aim manoeuvre before.
If you still choose to fire, the next action will be an Attack, All-Out Attack or Move and Attack. Another roll against Guns, Artillery or Gunner is made and the projectile(s) are treated as a non-homing “dumb” attack.
Note that in Transhuman Space, homing projectiles fired without an Aim and Lock still count as “stabilized”, so treat ranges as 30% less than actual for purposes of determining range penalties.
Gestalt ammo also counts as stabilized (THS:CT p.64 and THS 3e p.157).

Laser Sights

Many weapons mount targeting lasers, also known as laser sights or laser spots.
Beam weapons often have a targeting spot option. The weapon projects a harmless spot of laser light, and increases its intensity when fired.
A targeting laser adds +1 to skill, even if an Aim maneouvre was not taken. This presumes that a shooter can see the spot.
If the laser spot was set to infrared, the shooter will need vision sensitive in this range to see it.
Targeting lasers are of limited use underwater. Green is hard to see, red does not travel far, and water absorbs infrared.
If you have a reflex sight and a targeting laser, you must choose to use one or the other, not both at once (High-Tech 4e p.156).

Laser Homing

Laser-homing ammunition locks on to a target designated by a laser. This is usually the firing weapon’s targeting laser, but can be another source.
If the laser is moved or deactivated after firing, the rounds continue to home in on their target. The round retains a “snapshot” of the target that was designated.
Laser-homing ammunition works with both visible and IR lasers. Cheap, knock-off or black-market ammunition may only work in the visible but the buyer may not be aware of this!
Laser-homing ammunition must be used with a designating laser. Without a laser, it is dumb, stabilized ammunition, not homing.
Smoke, dust or other factors may prevent laser designation.
The targeting laser gives a +1 to Aim and Lock and designation gives +1 to the Homing Attack roll.

Gestalt Ammunition

Gestalt ammunition counts as stabilized, so treat ranges as 30% less than actual for purposes of determining range penalties.
Rapid fire bonus to hit (A7) is for 1.5x the number of rounds actually fired. Recoil is reduced by 1 for determining number of actual hits.
Below is a list of Ranged Attack Modifiers modified and annotated for use with Transhuman Space 4e.
When making a ranged attack, Homing Attack or Aim and Lock figure your effective skill by:
1. Taking your base skill with your ranged weapon. A projectile making a Homing Attack uses a base skill of 10.
2. Applying the target’s Size Modifier (SM), rounding up.
3. Modifying for the target’s range and speed, rounding up; see Size and Speed/ Range Table (Basic Set p.B550).
Remember, add range in yards to speed in yards/sec and take the modifier from the total.
Adjust for elevation (p.B407) if necessary.
Use actual adjusted range for Aim and Lock or firing of “dumb” unstabilized rounds.
Use 0.7 of actual adjusted range for stabilized and Gestalt ammo.
Ignore elevation for beam weapons.
Ignore range for Homing Attacks. Range Ruler here.
4. Applying the relevant conditional modifiers below.
Modifiers are cumulative, but combined visibility penalties cannot exceed -10.
If any modifier marked with an asterisk (*) applies, adjusted skill after all modifiers cannot exceed 9.
A roll of the calculated number, or less, is a hit.
If using rapid fire, you score one extra hit for every full multiple of Recoil by which you make your attack roll.

A1. Attacker’s Manoeuvre

A1 modifiers do not apply to Aim and Lock or Homing Attack
  • All-Out Attack (Determined): +1
  • Move and Attack: -2 or -Bulk of weapon, whichever is worse.
  • Ranged Rapid Attack: 2 shots at -6 each. Uses an Attack or All-Out Attack and requires a weapon with RoF 2+.

A2. Attacker’s Situation

A2 modifiers affect Aim and Lock and Shooting. They have no effect on Homing Attack roll.
  • Affliction (coughing, retching, etc.): see Afflictions (p.B428)
    Afflictions that add a penalty to DX add an equal penalty to Guns, Gunner, Beam weapon or Artillery skill for Aim and Lock or Shooting.
  • Bad footing: -2 or more (GM’s option)
  • In Close combat: a penalty equal to the weapon’s Bulk statistic (see Weapons for Close Combat p.B391)
    Aim and Lock cannot be attempted if in close combat. No effect on Homing Attack roll of projectiles already in flight.
  • Damaged weapon: -HP of damage received last turn (maximum -4). This modifier may persist until weapon is repaired.
  • Major distraction (e.g., all clothes on fire): -3 or more (GM’s option)
  • Minor distraction (e.g., part of clothes on fire): -2
  • Shock: -HP of injury received last turn (maximum -4)
  • ST below that required for weapon: -1 per point of deficit.
  • Overheating: For pistols, rifles, SMGs, and shotguns, reduce Acc and Malf. by 1 after firing 225 rounds in under a minute. See Sustained Fire 4e HT p.85-86.

A3. Attacking from Moving Vehicle or Mount

The increased relative motion between the firer and the target will affect the accuracy of homing projectiles.
A3 modifiers are applied to Aim and Lock, Shooting and Homing Attack.
If weapon is not in a stabilized mount, the combined bonus for Accuracy, Aim, bracing, and targeting systems cannot exceed the vehicle’s Stability Rating (SR).
  • Air vehicle: -1 if handheld weapon, 0 otherwise.
  • Exposed rider hanging on side of vehicle/mount and shooting over/under it: -6
  • Ground vehicle, good road: -1 if handheld weapon, 0 otherwise.
  • Ground vehicle, bad road: 0 if stabilized turret or stabilized open mount; -1 if fixed mount, hardpoint, or carriage; -2 if external open mount; -3 if handheld weapon.
  • Ground vehicle, off-road: -1 if stabilized turret or stabilized open mount; -2 if fixed mount, hardpoint, or carriage; -3 if external open mount; -4 if handheld weapon.
  • Space vehicle: 0
  • Turning in exposed saddle/seat of vehicle/ mount to fire at foe behind: -4
  • Vehicle/mount dodged last turn and you’re not operator/rider: -2, or -4 if flying.
  • Vehicle/mount failed control roll: penalty equal to margin of failure.
  • Water vehicle, calm water: 0 if stabilized turret or stabilized open mount; -1 if fixed mount, hardpoint, or carriage; -2 if external open mount; -3 if handheld weapon.
  • Water vehicle, rough water: -1 if stabilized turret or stabilized open mount; -2 if fixed mount, hardpoint, or carriage; -3 if external open mount; -4 if handheld weapon.

A4. Opportunity Fire

Aim and Lock can only be used with Opportunity Fire if the area watched is only 1 hex (no modifier).
The projectile is considered to have locked onto a geographical location rather than an individual. The homing round will hit anyone or anything that happens to be in that hex.
This mode of using homing projectiles cannot be used with targeting specific body parts or areas.
  • Checking target before firing: -2
  • Hexes watched: 0 if 1 hex; -1 if 2 hexes; -2 if 3-4 hexes or a line; -3 if 5-6 hexes; -4 if 7-10 hexes; -5 if 11+ hexes watched.

A5. Aiming and Targeting

The A5 modifiers come into effect “after the trigger is pulled”. They are applied to Homing Attack and are applied to Shooting if an Aim action preceded it.
A5 modifiers are not applied to the Aim and Lock success roll.
A player may make one or more Aim manoeuvres before an Aim and Lock, the modifiers being applied to the Homing Attack roll. 
  • Aim for one turn: +Accuracy (Acc) of weapon
  • Scope: extra +1 per second of Aim, to a maximum of the Scope Bonus
  • Extra Aim: +1 for 2 seconds, +2 for 3 seconds or longer. Extra Aim Bonus cannot exceed weapon Acc or Scope Bonus, whichever is lower. The Precision Aiming skill (HT 4e p.84) may grant additional bonuses.
  • Range known. +3 to Acc or Scope Bonus. Requires a Ready action to adjust sights or switch aimpoint.
  • Laser sight: +1 (also gives this +1 bonus if no Aim action preceded the shot)
  • Match-grade Ammunition: +1 to weapon Acc.
  • Braced weapon. Weapon rested on sandbag, car, wall or other object or long arm used prone and with a bipod: gives +1 if stationary and took a turn to Aim.
  • Pistol used two-handed: +1 if took a turn to Aim. Multiply minimum ST by 0.8 and reduce Bulk by 1.
  • Bipod: Use of a bipod changes minimum ST for weapon to ⅔rds its value. Long arm used prone and with a bipod: +1 if stationary and took a turn to Aim.
  • Tripod or similar flexible mounting, arm mount etc: +2 Acc for bracing.
  • Fixed Mount such as hardpoint, turret etc: +4 Acc for bracing.
  • Shooting Long arm with sling: Treat as braced.
    Takes one Ready manoeuvre per -1 Bulk of the weapon to prepare; a successful Fast-Draw (Long Arm) roll halves this time (round down). Leaving the position takes two Ready manoeuvres, or one with Quick-Sheathe (Long Arm) and a successful Fast-Draw (Long Arm) roll.
  • Firing a long arm with the stock folded or removed improves Bulk by 1, but removes the stability that resting it against the shoulder provides. Apply -1 to Acc and +1 to Rcl (unless Rcl is 1), and multiply ST by 1.2, rounding up. Using any sling or a shoulder rig on a stockless long arm avoids the Rcl and ST modifications, but not the Acc penalty. It does not count as braced.
  • Vehicular targeting system: +1 to +3 if shooter took a turn to Aim
  • Unfamiliar weapon or targeting system: -2
On a moving vehicle, the combined bonus for Accuracy, Aim, bracing, and targeting systems still can’t exceed the vehicle’s SR, unless stabilized (p. B548).
The combined bonus for sights, scopes, and/or targeting computers cannot exceed the value of the weapon’s base Accuracy.
A scope or similar device gives a +1 bonus to hit per full doubling of magnification if you take one or more Aim manoeuvres.
With a fixed-power scope, you must Aim for at least as many seconds as the scope bonus. With a variable-power scope, you may Aim for fewer seconds but this reduces the bonus by a like amount.
The Acc bonus and related bonuses are lost if any of the following occurs:
  • You lose sight of your target;
  • Switch targets;
  • Make an attack roll;
  • Move more than the step allowed by the aim manoeuvre;
  • Attempt a defense roll;
  • Fail the Will Roll after being injured;
  • Choose a different manoeuvre from aim (e.g., ready to reload);
  • Switch weapons or unbrace a braced weapon
  • Switch between sights, or otherwise change your weapon’s mode of use

A6. Other Actions by Attacker

Affect Aim and Lock and Shooting. Affect Homing Attack unless stated.
  • Unfamiliar aiming system, mounting, action etc: -2
  • Weapon in bad repair: -4 or more
  • Dual-Weapon Attack: -4/-8 with primary/ off hand (-4/-4 with Ambidexterity)
  • Off-hand attack: -4 (no penalty with Ambidexterity)
  • Reflex sight adds +1 Guns/ Gunner/ Beam weapon skill at 300yds or less. If you have a reflex sight and a targeting laser, you must choose to use one or the other, not both at once.
  • One-handed shooting of long arm: Multiply ST by 1.5, or 1.2 if sling used, rounding up. Weapon becomes unready unless shooter has 2x weapon ST, or 1.7x with sling.
  • One-handed shooting for bullpup long arm or long arm with magazine in grip: Multiply ST by 1.2, rounding up, or no modifier if sling used. Weapon becomes unready unless shooter has 1.7x weapon ST, or 1.5x with sling.
  • Long arm fired one-handed and held against heavy object. No ST multipliers but does not count as braced (A5).
  • Limp-wristed gangsta-poseur shooting: -1 (Must be treated as unsighted shooting. Cannot be braced and no bonus for two-handed grip)
  • Pop-up attack: -2, and no Aim possible. (Cannot be used with Homing attack)

A7. Rapid fire or Multiple Projectiles

A7 modifiers are “after the trigger is pulled” so are applied to Shooting and Homing Attack, not Aim and Lock.
Gestalt ammunition gets the bonus for 1.5x the number of rounds actually fired. A 10 round burst gets the +3 bonus for 15 rounds.
 0 if 2-4 shots;
 +1 if 5-8 shots;
+2 if 9-12 shots;
+3 if 13-16 shots;
+4 if 17-24 shots;
+5 if 25-49 shots;
+6 if 50-99 shots;
+7 if 100-199 shots;
+8 if 200-399 shots;
+9 if 400-799 shots;
+10 if 800-1,599 shots;
+11 if 1,600-3,199 shots;
+12 if 3,200-6,399 shots;
Fast Firing: (Pump or lever actions up to double tabled RoF, Semi-automatics, beam weapons and double action revolvers up to triple). Rcl increased by +1, Attack roll modifier equal to actual number of rounds fired.
An attack scores one extra hit for every full multiple of Recoil by which you make your Attack roll. The total number of hits cannot exceed shots fired.

A8. Target

A8 modifiers apply to Aim and Lock, Shooting and Homing Attack.
To attack hit locations or weapons, use the penalties under Melee Attack Modifiers (p. B547).
If the target has cover, you can either choose to take no penalty and roll hit location randomly (shots that hit a covered location always strike full cover, and hit partial cover on 4-6 on 1d) or target an exposed hit location (add an extra -2 if only partly exposed).
  • Very light cover (solid cover exposing ¾ of body): -1
  • Shooting through light cover (solid cover exposing ½ target): -2
  • Medium cover (Solid cover exposing just ⅓): -3
  • Heavy cover (solid cover ¼ or less exposed): -4
  • Targeting the face, hand(s) or weapon of an enemy firing from cover: no penalty for cover, usual penalty for body part (see below).
  • Target behind someone else: -4 per intervening figure
  • Target crouching, kneeling, sitting, or lying down: an extra -2 to hit torso, groin, or legs
  • Target only partly exposed: -2
  • Shooting at narrow apertures or object: Use SM of item.
  • Hit location for humans:
    • 0 for torso,
    • -2 for arm or leg,
    • -3 for groin or pelvis,
    • -4 for hand or foot,
    • -5 for face,
    • -7 for skull; impaling and piercing attacks can target vitals at -3 or eyes at -9
  • Weapon, to damage: -5 to hit a reach “C” weapon (e.g., knife or pistol); -4 to hit a reach 1 weapon (e.g., broadsword, baton, bangstick); -3 to hit a reach 2+ weapon (e.g., spear or rifle)

A9. Visibility

A9 modifiers apply to Aim and Lock, Shooting and Homing Attack. Visual capabilities of the shooter and the homing round may differ!
  • Blind, target completely invisible, or in total darkness: -10*
  • Cannot see foe: -6, or -4 if you know his location to within 1 yard*
  • Partial darkness, fog, smoke, etc.: -1 to -9 (GM’s option)
  • Target has light concealment (e.g. bushes): -2
  • A telescopic sight removes -1 of darkness penalties. A telescopic sight with an illuminated reticle removes -2 of darkness penalties.
  • A reflex sight removes -3 of darkness penalties. A micro-reflex sight for a pistol removes -1 of darkness penalties.
  • Night vision goggles that limit depth perception: -3 (THS-era devices are likely to use holographic or AR technology that removes or reduces this penalty).