It appears to be looking for a base-game sound file ('demo-gunshot-sounds'?) that has been removed or renamed in 0.18.2.

Got it. I'll fix it and update today.

Thank you. I downloaded the update, but I still get this when I load the mod:

1.280 Mods to disable:Failed to load mods: __assault-rifle__/data.lua:1: __assault-rifle__/prototypes/item/rifle.lua:32: attempt to call global 'make_heavy_gunshot_sounds' (a nil value) stack traceback: __assault-rifle__/prototypes/item/rifle.lua:32: in main chunk [C]: in function 'require' __assault-rifle__/data.lua:1: in main chunk stack traceback: [C]: in function 'require' __assault-rifle__/data.lua:1: in main chunk

Okay, I see now. I'll make sure to thoroughly test it this time. I'll get on this right away. I'm very sorry for the inconvenience.

Now it is fixed. :-) Thank you. And no worries. Thank you for making it.