Using:
Minecraft 1.20.1 Forge 47.4.8
Framework 0.7.15, geckolib 4.7.4, curios 5.14.1
(all latest to date)

from ScorchedGuns-0.4.0 to ScorchedGuns-0.4.2

Guns do not lose durability when fired, but they do lose durability when hitting a melee target. This does not happen in a singleplayer world, the weapon loses durability normally. It also works correctly in ScorchedGuns-0.3.9
I am not using any additional mods other than those mentioned above.