It sounds like youre on the Mida quest. So what I did was pick a planet that I liked, and had some things to do on. I think it was the EDZ in this case. I hit public events, patrols, high value targets, everything. I spent a few hours shooting around and knocking things out. After a while, I had built up a wealth of guns and armor from the public events, and a ton of tokens. Turning them in in bulk to Devron. I think it took two or three hours, but eventually, I had all the scout rifles I needed.