Gun Generator: v0.1

[Jinumon]

Hello everyone!

So I've been working on the idea of a gun generator for quite some time. I've seen plenty of people recommend "The Cole Method," but I'm not much one for physics, and I was trying to come up with something that fits more into the game than into realism. Anyway, I wanted to run a Firefly game, but wanted a lot more variety to the TL9 conventional firearms. So, with that in mind, and using David Pulver's "Blaster and Laser Design" from Pyramid 3/37: Tech and Toys II as a basis, here's what I've come up with. But first, a few notes.

1) This is the very definition of a work in progress. If you see any blatant flaws, holes, or mathematical errors, I'd really appreciate you letting me know.

2) I'm hoping to update this as I get feedback and continue to work on it.

3) These rules will not allow you to recreate the standard weapons from GURPS: Ultratech, though it can get you pretty close. Those (and an ass-ton of algebra and playing with numbers) have given me the figures I've arrived with. These are simply as close as I could get.

4) There are some problems I simply could not solve on my own (like Range formulas), and so I made arbitrary decisions and have decided to post here in hopes that the community might be able to solve the problems I couldn't.

Gun and Launcher Design
Tech Level
For now all I have a decent workup is for TL 9. My experiences here and how well it's received will inform any work I do on later Tech Levels

Projectile
Again, right now all I have is for conventional guns. This is the very first workable version.
Conventional (TL9): A heavy, metal projectile, fired from a caseless cartridge. It inflicts piercing damage. Choose the type of piercing damage the weapon inflicts.

Barrel Array
This is the weapon's barrel and rifling system, which helps determine range. Decide if the weapon has a tiny (x0.1), very small (x0.25), small (x0.5), medium (x1), large (x2), very large (x4) or extremely large (x8) barrel-array relative to typical weapons of its class. Most weapons use a medium array, but a smaller array means reduced range with some saving in weight, while a larger array is heavier but longer-ranged.

Automation
Decide on the level of automation, which determines rate of fire.
Single Shot: The firearm can only fire one shot per second, but is lightweight.
Semi-Auto: The firearm can be built to fire at up to RoF 3.
Light Automatic: The firearm can be built to fire at RoF 4 to RoF 10.
Heavy Automatic: The firearm can be built to fire at RoF 11 to RoF 20.
Rotary: The firearm can be built to fire at up to RoF 40.

Damage Dice
Choose the dice of damage the weapon inflicts. The greater the damage, the heavier the weapon will be. Partial dice of damage can be specified as a decimal value. This will be converted to dice plus adds, but the decimal value is used for all other design calculation. Man-portable weapons should deal between 2d and 15d of damage, with pistols and carbines being nearer the bottom and anti-armor weapons being nearer the top.

Empty Weight
Calculate the weight in pounds based on the design decisions and this formula:

Empty Weight = (D x S / P)² x B x A
D is dice of damage.
S is 2 for most guns, or 1 for “super” versions of non-superscience guns.
P is 5 for conventional firearms.
B is for the barrel-array value: 0.25 for tiny, 0.5 for very small, 0.8 for small, 1 for medium, 1.25 for large, 1.6 for very large, or 2 for extremely large.
A is for automation value: 1 for single-shot, 1.25 for semi-auto or light automatic, 2 for heavy automatic, and 3 for rotary

Configuration
Holdout: The weapon is handheld, but may be shaped like a pistol or some other small device. This reduces Accuracy but lowers Bulk.
Pistol: The weapon uses a standard pistol grip.
Rifle: The weapon uses a carbine or rifle format with a shoulder stock and grip.

Weapon Statistics

Damage
Record the dice of damage chosen for the weapon. Conventional firearms have no armor divisor.

Accuracy
Accuracy depends on the weapon's configuration: 1 for Holdouts, 2 for Pistols, and 4 for Rifles.

Range
The weapon's half-damage and maximum ranges depend on the barrel array and dice of damage. Use the formulas below. Round range to two figures.
1/2D Range (yards) = D x D x Rb x Rt
D is dice of damage.
Rt is 22 pi-, 19 for pi, 16 for pi+, or 13 or pi++
Rb is based on the barrel-array: 0.1 for tiny, 0.25 for very small, 0.5 for small, 1 for medium, 2 for large, 4 for very large, or 8 for extremely large

Max Damage = 1/2D x Rb
Rb is based on the barrel array: x3 for tiny, x4.5 for very small, x6 for small, x9 for medium, x12 for large, x18 for very large, or x24 for extremely large.

Rate of Fire
Choose a RoF based on the weapon's level of automation and record it.
Single Shot: The firearm can only fire one shot per second, but is lightweight.
Semi-Auto: The firearm can be built to fire at up to RoF 3.
Light Automatic: The firearm can be built to fire at RoF 4 to RoF 10.
Heavy Automatic: The firearm can be built to fire at RoF 11 to RoF 20.
Rotary: The firearm can be built to fire at up to RoF 40.

Shots
Firearms are loaded with magazines, either classified as compact “Sticks” or bulkier, more efficient “Boxes.” Decide on how many rounds you want a chosen magazine to hold, and record the weight of the ammo. Then, calculate the weight of the empty magazine using the following formulas:
Stick Weight = (square root of Shots) x Wa x 6.7
Box Weight = (cube root of Shots) x Wa x 2.4
Wa is the weight per shot

Once the weight of the empty magazine has been calculated, add it to the weight of the ammo to determine the weight of a loaded magazine.

The size and type are typically up to the GM or the inventor of the weapon. However, keep in mind that guns with a magazine heavier than 1/2 of their empty weight are particularly unwieldy (additional -1 to Bulk, discussed later).

Reloading Time
The reloading time depends on the type of magazine: 5 seconds for Box magazine, 3 seconds for Stick magazines.

Weight
The weight of a firearm is its empty weight modified by the weight of a loaded magazine.
Weight = Empty Weight + Loaded Magazine Weight

Strength Requirement
Calculate the weapon's ST requirement using the formula below with loaded weight.
Pistol or Holdout ST = (square root of weight) x 6.3
Rifle ST = (fifth root of weight) x 6.3

Round to the nearest whole number.
If weapon is a rifle, append a dagger after ST to indicate two hands are used.

Bulk
Calculate Bulk using the formula below and express it as a negative number.
Bulk = (square root of weight) x SB
SB determined from the configuration: 1.5 for rifle, 1.25 for pistol, 1 for holdout.

Round Bulk to the nearest whole number and tack on a minus sign. However, the minimum Bulk is -3 for a rifle, -1 for a pistol, or 0 for a holdout; the maximum Bulk is -10

Recoil
Recoil depends on the size of ammunition fired from the firearm: 2 for pi- or pi, 3 for pi+, and 4 for pi++.

Cost
Cost depends on weight.
Cost = Empty Weight x Bc
Bc is $300 for conventional guns

Legality Class
Calculate the weapon's LC. The basic LC is 3 for conventional firearms. Reduce LC by 1 if the weapon exceeds RoF 3 or by 2 if the weapon exceeds RoF 20, and by 1 if it weight over 15 lbs. (loaded).

Skill Required
Any rifle configuration with a Bulk of -4 or greater, as well as Bulk -3 rifles with a RoF 3 or less uses the Guns (Rifle) skill.
Rifles that exceed RoF 3 and have a Bulk -3, as well as all Pistols that exceed RoF 3 use the Guns (SMG) skill.
Pistols with a RoF 3 or less use the Guns (Pistols) skill.