Why can we find guass and not buy ammo?

Because when you find a gauss rifle it's lostech, and nobody makes gauss ammo.

Really does suck when you get a rifle and no ammo for it. I tend to reload the last save and roll those dice again when that happens.

Gauss ammo is a rare "drop" in shops. And only in systems with the "Former Star League Presence" tag, IIRC.

EDIT: You also can get it by playing Flashpoints with "LosTech" as reward,

You can actually just buy it? Well damn. I wonder how much I missed out on just by not scrolling down that far? Thanks for the heads up though.

Do you play the latest version? I think, it wasn´t sold in shops in the very first game versions. It was added with patches a bit later.

Yeah, it's up to date. But I don't often scroll down to ammo as I've usually got more than I'm ever going to use. I'll keep an eye out from now on though.

Try Kimi I've always found it a good shop for guass ammo