Some rules for modern firearms, loosely stolen from Boot Hill. I'd probably make it a d20 system, but I'm writing it for kahva to possibly maybe use in an upcoming cyberpunk game so it's going to be d100. The math shouldn't be hard to convert either way.
Wounds
When someone takes a wound, they roll 1d6 (with any relevant modifiers). If the roll is 0 or below, it's a superficial scratch. If the roll is 6 or higher, the afflicted dies instantly. Otherwise, their Strength score is reduced by the value of the d6 multiplied by 10. If their Strength is reduced to 0, they are unconscious and bleeding out. If a specific location is hit (from a critical success on a Firearms roll, for example), it may have other effects.
Shooting
Every round of combat (about 5 seconds), you can shoot - this is much slower than you can actually fire most guns, of course, but it's handy for the sake of simplicity, and you can assume you're just firing more than one bullet if it bothers you. It also takes a round to reload. To determine whether or not you hit, roll 1d100 under your Firearms skill. The target is hit and takes a wound on a success. If the target is behind less than 100% cover or at long range for your gun, reduce your skill for that roll by half. If you roll a critical success (a success with a 0 as the second digit of your roll), you get to pick exactly where the shot hits. Headshots kill instantly, arm or leg shots generally incapacitate the limb in addition to causing a wound as normal. Normally, all shooting is simultaneous, but in situations where speed really matters - a quickdraw shootout, breaching a room - the GM may allow both sides to roll to see who shoots first.
Armor
There are four classes of armor: light, medium, heavy, and vehicle. Vehicle represents light armored vehicles, not tanks. A regular unarmored vehicle's body generally counts as light armor. Each gun also has an armor penetration value, which is reduced by one at long range. Guns with a penetration value equal to the target's armor penetrate automatically. Light armor can take three hits from guns that don't penetrate it before it breaks, while medium armor can take four, heavy armor five, and vehicle armor unlimited. Heavy armor also can prevent one headshot caused by a critical success from being an instant kill (it still causes a wound as normal).
Full-Auto
Fully automatic weapons have a die, 1dX (a SMG is 1d6, for example). You can choose to fire X bullets instead of just one. If you succeed your roll, 1dX of those bullets hit the target.
Shotguns
Shotguns, when fired at a target within close range, cause 1d4 wounds instead of just one.
| Weapon | Wound Mod | Range | Penetration | Ammo | Other |
|---|---|---|---|---|---|
| Stun Gun | - | 5/20 | None | 1 | no wound, roll vs stun |
| Pistol | 0 | 30/100 | None | 20 | - |
| Heavy Pistol | 0 | 40/120 | Light | 10 | - |
| PCC | 0 | 50/150 | None | 20 | - |
| SMG | 0 | 50/150 | None | 30 | full-auto 1d6 |
| PDW | 0 | 40/120 | Light | 30 | full-auto 1d6 |
| Light Rifle | 0 | 100/300 | Medium | 10 | - |
| Assault Rifle | 0 | 100/300 | Medium | 30 | full-auto 1d4 |
| LMG | 0 | 100/300 | Medium | 100 | full-auto 1d4, heavy* |
| Rifle | +1 | 150/450 | Heavy | 5 | - |
| Battle Rifle | +1 | 150/450 | Heavy | 20 | full-auto 1d3 |
| Sniper Rifle | +1 | 200/600 | Vehicle | 5 | heavy* |
| Shotgun | 0 | 30/100 | None | 8 | - |
| Combat Shotgun | 0 | 25/75 | None | 10 | full-auto 1d2 |
*heavy weapons are cumbersome and awkward to carry, especially during arduous physical activity
Explosives
To throw explosives, roll under your Explosives skill - this takes a round just like shooting a gun. Grenade launchers and RPGs use your Firearm skill instead. If you succeed, the explosive goes exactly where you intend it to. Otherwise, roll 1d3: 1. it hits some of the intended targets, 2. it hits nothing, 3. it hits an unintended target (all determined by the GM and common sense). If you roll a critical success, thrown explosives are perfectly timed and can't be evaded or thrown back. Otherwise, the targets of a thrown explosive can roll to a) throw the explosive back (it has a 50% chance of exploding in their face), b) kick the explosive away harmlessly, c) jump on the explosive, taking twice the normal wounds but preventing anyone else from getting injured, or d) get behind any available cover. Explosives deal 2d4 wounds within the close area and 1 wound within the far area. Thrown explosives ignore all armor less than vehicle, launched explosives ignore all armor.
| Explosive | Area | Other | |
|---|---|---|---|
| Stun | 20 radius | no wounds, roll vs stun | |
| Improvised | 5/10 radius | 10% chance of dud | |
| Grenade | 20/40 radius | - | |
| Grenade Launcher | 10/20 radius | standalone has 6 ammo, rifle attachment has 1 ammo | |
| RPG | 30 cone/20 radius | inaccurate*, penetrating** |
*firearms skill reduced by 1/2 vs any target smaller than a car
**cone of high damage goes through walls or heavy vehicle armor
Melee
If people are engaged in melee combat, they can do nothing else that round. All participants roll their Melee skill, and on a success they can a) hit and causing a wound, b) flee from that melee, or c) prevent one opponent from hitting. On a critical success, one can choose the location of their wound as with a gun (although headshots are not always instant kills with all melee weapons) or prevent all opponents from hitting. Armor functions exactly the same for melee weapons as it does for guns.
| Weapon | Wound Mod | Penetration | Other |
|---|---|---|---|
| Taser | - | None | no wound, roll vs stun |
| Unarmed | -2 | None | - |
| Rifle Butt/Pistol Pommel | -1 | None | - |
| Brass Knuckles | -1 | None | - |
| Club | -1 | Light | - |
| Knife | 0 | Light | - |
| Hatchet | 0 | Medium | - |
| Sword | +1 | Medium | - |
| Battleaxe | +1 | Heavy | heavy |
