Gun Generator: v0.1

[Dwarf99]

Well, upon pulling out High Tech the 9x19 has 160 yards (closer to 452) ,the 9x18 has 110 yards (closer to 310x)

Of note with other rounds the 7.63x25 (~.3) has around x600 compared to the 7.62x39's x1666, the 7.62x51's x3333, and the 7.62x54's 3,666. So, maybe we should have some factor of case length in there too. Maybe ball-park it around Caliber x(case ratio x200)? That's obviously just a ball park figure, and I don't really know if it'll work for the majority of rounds.

[gilbertocarlos]

What about projectile weight?

[Jinumon]

Originally Posted by gilbertocarlos

What about projectile weight?

I actually just worked out the figure for that, after yet another ass-ton of math (about 2.5 hours and 6 pages of scribbles). But I've recently discovered that it plays a closer role with damage and range than I thought, and so I'm waiting to post it until I've got a better understanding of the big picture. I should have it up later today.

[Dwarf99]

Originally Posted by Jinumon

I actually just worked out the figure for that, after yet another ass-ton of math (about 2.5 hours and 6 pages of scribbles). But I've recently discovered that it plays a closer role with damage and range than I thought, and so I'm waiting to post it until I've got a better understanding of the big picture. I should have it up later today.

You could simplify it to a 'density factor' kind of like you did with Barrel Array. Assume lead is x1 and take the ratio of mass relative to lead as the density factor, then list some for convenience.

[Jinumon]

Sorry for not posting earlier, but I am just a few number crunches away from a full-fledged comprehensive system for Conventional Firearms.

[Dwarf99]

:D Awesome!

[Barghaest]

Yeah, I miss the old 3E Vehicle rules... the system that had in it for weapons I used to re-engineer hand-held firearms for a more compatible system... that way if I needed a new type of gun it fit into the others exceedingly well.

[David L Pulver]

Originally Posted by Barghaest

Yeah, I miss the old 3E Vehicle rules... the system that had in it for weapons I used to re-engineer hand-held firearms for a more compatible system... that way if I needed a new type of gun it fit into the others exceedingly well.

My hopefully nearing completion Vehicles Design manuscript has an updated gun generation system. It's somewhat more complex than the 3e version but seems to provide greater accuracy.

Here is output from a sample weapon, an attempt at a rough design of a typical Bofors 40mm automatic cannon:

40mm Autocannon (TL6): A heavy automatic cannon often installed as an anti-aircraft gun on warships. It is conventional 40mm L56 rifled heavy automatic weapon (CE 365 kJ) using cased ammunition. It fires a 2 lb. projectile (LD 4, DV 6.5) at 2,760 feet per second. Typical ammunition includes SAPHE (on table), AP with 6d¥4(2) pi++; HE-AB with 6d+2 [2d] cr ex. A solid projectile is 6d¥6 pi++.

TL 6 40mm Automatic Cannon Dam 6d¥6 pi++ Acc 5 Range 3,000/11,000 Wt. 871/57 RoF 4 Shots 8(3) ST 38M Rcl 2 $91,000 Power 0

L56 = barrel length in multiples of caliber.
CE = charge energy in kJ (muzzle energy assuming optimum barrel length)
LD = length to diameter ratio of projectile.
DV = specific gravity of projectile.
SAPHE = semi-armor piercing high explosive
HE-AB = high explosive air burst

Something more small-arms-ish, an attempt to reverse-engineer the larger MGs from Aliens:

10mm Machine Gun (TL9): An ultra-tech caseless “pulse rifle” weapon. It is an electrothermal-chemical 10mm L57 rifled heavy automatic (CE 10 kJ) with caseless ammunition. It fires a 0.047 lb. projectile (LD 4, DV 10) at 2,990 feet per second. It requires 10 kW (EPS 0.5 kJ). Typical ammunition is a solid (on table) or APHC with Dmg 10d(2) pi.

TL9 10mm Machine Gun Dam 10d pi+ Acc 5 Range 1,400/5,900 Wt 16/13.6 RoF 15 Shots 200[5] ST 14M Rcl 2 Cost $6,700

[David L Pulver]

Originally Posted by Varyon

Vehicles for 3e scaled 1/2D with the square root of damage (well, square root of bore size, but damage was linear with that) rather than with damage squared. Max scaled with the square root of 1/2D.

More realistically, 1/2D should be determined entirely by shape and weight of the projectile. For TL 4 weapons, I found that multiplying caliber (in inches) by 100 gives around the same 1/2D Range (in yards) as found in Low Tech. Max is more complicated, but 10x 1/2D is fairly consistent of GURPS weapons, so you could go with that.

For supersonic projectiles, the factors I use are projectile weight (increases range), muzzle velocity (increases range), diameter (produces drag), projectile length to diameter ratio (increases range) and a scaling factor based on diameter that simplifies some logarithmic effects and the tendency of larger-caliber artillery to have better nose shapes.

[Dwarf99]

I hope it's forgiveable to ask if the OP is still doing something with this.