[3e] Statting a CTA weapon

[Varyon]

Originally Posted by GURPS Fox

But what about the ammunition? Like how to stat the weight, cost, and volume of a CTA round?

I can do the damage figures. The problem here is the ammunition's weight, cost, and volume modifiers. For example, if I want to make a CTA gun, what modifiers are needed?

It looks like you have the mass and volume already, although your mass doesn't match any of the ones I can find here. The thing that looks to be unique about these rounds is their telescoping design that allows them to have a short length. Offhand, compared to normal munitions of the same type, I'd say this option cuts length to somewhere in the ballpark of 70% normal (which will have the same effect on volume). Weight would probably be a bit higher, but leaving it unchanged is probably acceptable. For cost, a mere mortal such as myself isn't going to be able to get a quote for military munitions, so we can't go off real-world pricing. As a general rule of thumb, however, GURPS often follows a trend of modifying cost by the square of the effect. In this case, that would mean double cost for the Telescoping option. I feel that's lowballing it, however, and would be more inclined to x4 or x5. Whether these are multipliers on top of the normal cost of ammo (so Telescoping APFSDS would be a total of x8, x16, or x20 cost, as APFSDS is a x4 modifier on its own) or if they follow the CF system (where xn is replaced by +x(n-1), you add up the CF's, then add 1 to get the multiplier; in this case, x2 becomes +1, x4 becomes +3, and x5 becomes +4 - so Telescoping APFSDS has a total CF of +4, +6, or +7, for x5, x7, and x8 CPS, respectively).