Mission 2: The Battle of Endor
After a mid-mission cutscene (after completing the main objectives in the starting area), you will come to a bunker. Kill the enemies and inside the bunker you'll find the "Barrage" in a weapon box. Pick it up and press D-Pad Left to equip it. Now continue forward with the mission until you need to eliminate more enemies. There will be lots of enemies spawning close together. It's easy to kill 5 of them with one hit. However, for the trophy you only need to kill 5 enemies total with 3 shots. Restart the checkpoint if you fail.
Here is a video guide with English commentary!
Here is a playlist of guides for this game!https://www.youtube.com/playlist?list=PL-HeW6XkKdULGSVKoX6Iu...