GURPS ULTRATECH ballistics?

[hal]

Finally Finished Modifying Doug's Original Ballistic spreadsheet for my purpose. I've done away with Doug's original set up listing Chamber Pressure, Barrel bore, Case Length, Chamber Bore, Barrel length, Bullet Mass, Aspect Ratio, Burn length, Projectile Caliber, and Total Accelerated Mass.

Instead, I'm using:

Bullet Mass, Bullet Mass in Grams, Velocity in Feet/sec,
Velocity in Meters/Sec, Kinetic Energy in Joules, Average Bullet Damage, GURPS Dam, Bullet Xsecton, Half Damage Range, Max Damage Range, Sectional Density, Loss Coefficient, Aspect Ratio, and Projectile Caliber

Bullet Mass in Grams is just a calculated conversion from Grains, it is only used for reference comparison (such as when someone talks in Grams and someone else talks in Grains), Kinetic Energy in Joules (Also for reference, not directly necessary in the calculations). All other values are used for calculations as necessary.

Here is a sample gun written up based on Greenhill Military Small Arms Data Book.

Bullet Mass in grains	193	
Bullet Mass in Grams	12.50618963	
Estimated Bullet Length	20.8 based on aspect ratio	
Velocity in Feet/sec	725	
Velocity in Meters/Sec	220.98	
Kinetic Energy/Joules	305.35	
AverageBullet Damage	6.4	
GURPS Dam	        2D-1	
Bullet Xsecton	        0.00008495	
Half Damage Range	313	
Max Damage Range	1157	
Sectional Density	0.147243056	
Loss Coefficient	0.002116065	
Aspect Ratio	2	L/Bore
Projectile Caliber	10.4mm
		
		
Name	Troopers M1878	
Cartridge	10.4x20R Swiss Ordinance	
Length	9.25 Inches	
Weight	1.625 lbs	
Magazine	6 Round Cylinder	
Muzzle Velocity	725 Feet per second	
		
Cartridge	10.4x20R Swiss Ordinance	
Bullet Weight in Grains	193

Note, I don't have access to the aspect ratio, but it appears that the aspect ratio should be around 1.8 to 2.1 (or about 2.0 for pistol rounds), and about 3 to 5 to 1 for Rifle bullets. For my own use, I'd have to guess as best as I can where I can.

As for using this with other game systems? For those who have GUNS GUNS GUNS by Greg Porter, it has rules for designing your own cartridges along with guns. At the very least, it can be used for making your own "Sci-fi" weapons to some extent. Is it 100% compatible with GURPS? Not really in the sense of damage values or anything else. But it does give you the tools to build your cartridges or weapon systems, assign real world values for weight, etc - and guidelines for stats for GURPS 3e rules - which should be enough to make these guns usable for GURPS 4e.

As long as you have the velocity in feet per second, the bullet weight in Grains, the Diameter of the bullet, and the Aspect ratio - the spreadsheet will give you some basis for what the designed weapon system should be for use with GURPS 4e.

The Next time I post to this thread with a weapon design, I will try and design a Sci-Fi type gun without using Caseless or anything else - just conventional rounds in an unconventional diameter etc - just to see what I can create.

Note: this does not calculate Weapon Accuracy based on barrel length, nor unconsumed propellants or what have you. All it does is give you damage, half/damage range, and Max Damage range. It is already known to produce results not in synch with GURPS HIGH GUARD, but it seems to do the job until such a time as someone publishes a Pyramid Article for designing conventional guns for use with GURPS 4e like they did with the Energy guns.

What might prove to be interesting is to see if the GGG rules (now called 3G3 if you buy the PDF version) can create a credible Caseless Round and stats for it, such that I might be willing to compare/contrast it against ULTRATECH's values. Might prove to be interesting.

:)