ok i can tell why most metal bands dont use 7 strings thats because there is no need to. a lot of dudes play a 7 string guitar thats tuned to an open chord and they have just enough strength in the first finger to chord it and thats boring but if thats what u feel thats what u feel . and now for the main point alot people have 7 strings but only play 3 strings why not just play a 3 string guitar ? scott ian of anthrax plays a 4 string guitar so he tells it like it is. so thats why many bands dont play 7 string guitars there is no need to they sound the same as a 6 string dropped and for the one dude who said something about slipknot well they dont use 7 string guitars

ok dudes peace