Best/Quickest way to get 42-80 range on runescape?

32atk 30str 2def 87mage 42range 45hp 45pray i recently did desert treasure and i plan on getting 94mage for barrage but i was thinkin i need somethin i can KO with So 80 range? I was thinkin rock and cannon I have 40M how many C' are needed?