*Note* Aside from the copper shortsword, the Flare Gun is one of the rarest weapons in the game, with a rating of blue when you open it in the menu.

Flare guns are usually found in chests hidden in caves, but the reason why it's rare is because nobody wants to go in a cave! Aside from getting really good stuff like Shurikens, going into caves is dumb and pointless. But after a long and boring time of searching, you should find a flare gun with 25-50 flares with it.

When using the flare gun against bosses (mainly the moon lord) be sure to not have anything equiped, except if you're using mining armor. There's a 50% chance of him getting weaker if you have mining armor. But if you're using anything else, it will make bosses stronger when you're using the flare gun. The boss will drop some bonuses if done correctly, but the bonuses are garbage and I would recommened trashing them.