This can only be earned in Salvo Mode. You should be able to earn this through normal play as you will have to play Salvo mode a lot to rank up. But, if you want to get it fast you can use the windows button method. Start a new single player Salvo mode game. Pick your five targets. If you don’t score a hit, press the windows button. Then go back into the app, choose Salvo mode again and there should be an option to continue. As long as the AI hadn’t taken its turn yet you should be back to before you picked your targets. Keep at this until one of your picks scores a hit.