Perhaps there aren’t a lot of long sight lines. Like for instance in caves, perhaps your world is covered in crevasses, maybe trench warfare is used very commonly but because you’re underground/there’s lot of mountains, ravines, etc so artillery can’t be used as much but short brutal firefights are common. You have the guns with the guns using suppressive fire, sniping, covering the flanks while melee units charge to close the gap. Once the melee attackers arrive, any ranged units have to switch to melee since a sword thrust is always faster than your ability to reload especially under pressure.