On my ESP AW-7 25.5" 7-string guitar I am trying to string it up for Drop-A. I've tried both .066 and .070 for the A string plus just a normal 6-string set. (10-46) Both have felt flappy, and sound flubby. I can't imagine I would need anything over .070 so I'm wondering what I could be doing wrong? It does look like the .070 is not sitting flush enough in the nut, but the .066 was fine.