Just to be sure.... Drop C - guitar tuned C, G, C, F, A, D yeah? With heavier strings, ie 10 - 52's or 11/12's then you shouldn't need to adjust the truss rod, and unless you know exactly what you're doing, I'd recommend against it. I changed my strat from 10's to 9's last night and it took a good while of tuning until it finally settled so be patient.......