I have this gun script and when I test it, only PC players can reload. I tried ContextActionService with no luck, and I tried a mobile-only GUI, which also had no luck.
This is the reloading part:
function onKeyDown(key,mouse)
key=key:lower()
if key=="r" or script.Parent.Name == "Assault Rifle [0]" and not reloading then
reload(mouse)
end
end
reloading is a variable.
The whole script is here.

3 comments
This was deleted because I deleted it :/
The only way to do this is through ContextActionService, I recommend you look at the API reference and or watch some tutorials on youtube to try and find out why it wasn't working.
keydown is deprecated