Question About Mics to use to record guitars?

I am in a small deathcore band trying to record an album, I can make great sounding drums (were using a set of cad mics) great b guitar (were recording line in) but Ive hit a wall with recording guitar, line in sounds dead, and the sm57 is not good enough to keep punch and clarity in lower tunings, what would be a better mic for me?! (please and thankyou)