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Old 09-27-2017, 11:25 AM   #56
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Re: GURPS ULTRATECH ballistics?

Based on reading online for reloading bullets and the like, part of the purpose of the brass casings for bullets was to act as a heat sink for the gun in an effort to keep it cool enough to fire (not the primary consideration to be sure!). Then there are those cartridge case designers who wish to insure that the cartridge with one design spec and would be dangerous to place in a pistol due to over pressurization effects - are deliberately made longer or what have you to insure that the rounds can't be placed in guns that it would be dangerous for.

3G3 (or Guns Guns Guns) made a point for designing your own weapon systems and even of cartridges, but I'm finding it maddening right now to incorporate something as simple as "bullet volume" and "Bullet Mass" simply because the formula required to determine volume was never listed in the book form or the PDF form of the material. When I use actual volumes for spheres, I can make my data match the tables given in the book (1:1 aspect ratio). However, when I attempt to create a formula that handles the 2:1 or higher aspect ratios, that is when I find my formula produces results that don't match the table. After all these years, I've NEVER noticed that bit of information.

According to the book form, which states that the volumes are based on Hemisphere plus cylinder volumes - simply halving the volume of a sphere will produce a hemisphere. Knowing that the Length to diameter ratio is supposed to be 2 to 1 gives me some means for estimating the height of the bullet as being equal to Aspect ratio x Diameter minus 1/2 diameter (for the hemisphere aspect). So, the formula for the volume would simply be 4/3 * R^3 * Pi all divided by 2 (for the hemisphere) plus 1/2 Diameter * R^2 x Height for the Cylinder.

I did find online, a program written in basic that estimates the volume of a rifle bullet that was boat tailed, squared bottom or other such - which if I can translate into VB.NET code, will probably work out nicer for getting better bullet masses or volumes than the GGG rules, but that's something else for a rainy day (for now). So, do I trust GGG 100% Not entirely. It is however, better than nothing - and we can't use GURPS VEHICLES 2nd edition rules for designing guns for use with 4e per se - but at least, for me, it keeps my mind occupied and out of trouble. ;)
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