I play a 5 string bass and the standard tuning is (as you can guess) BEADG but i play in Drop G (GCGCF) and i was wondering what gauge string i should use because the ones im using are old and too thin and when i try to play even though i use a 5 string the fith string sounds flat and dull and impossible to hear over the chug of a guitar ot the boom of a bass drum so if anyone has any ideas about what gauge of strings i should use i would much appriciate it if they could give me an idea thanks.
If you're tuning your E string down to C, you should probably be using the B string from a 5-string set.
What you really want is the bottom 5 strings from something like the Conklin 7-string set that is made for a low F# tuning. You'd only be a half-step up from that across all your strings. Unlikely to break any strings that way, and you should get plenty of tension for a good strong tone instead of your strings being all floppy.