I'm a pedant. I can't help it. So here goes... there's no such thing as 'rapid fire range'. Rapid Fire is a weapon type that has specific abilities, which include firing multiple shots at half range or less. But firing those multiple shots isn't 'rapid firing'.
I guess you could say whenever you shoot a Rapid Fire weapon you are are within 'rapid fire range' of the particular weapon you're 'rapid firing', but it's incorrect to restrict it to shots under half range specifically.
It's not just Demonus I'm singling out here btw, it happens A LOT on 40k forums.
Again, I apologise for my pedantic nature, please feel free to give me a stiff ignoring.
Peace.