Because it didn’t spread flames, there were little flying sparks near the surroundings. And he didn’t need to put up with any clouds of dust due to the explosions. Thus, he didn’t relax on the aiming even if there was a considerable distance.
Though Shin didn’t know it, it was the adventurers who had been dispatched to observe the Wraith Plains, the knights squadron. They accidentally encountered the Skull Faces which had left the plains, and it became a state of war.