Yesterday, the guitarist and I decided to start tuning everything down 1/2 step for several reasons: many of the artists who we cover recorded that way, it fits both our vocal ranges better, and it makes our instruments feel better. While I keep a 5 string with flats on hand for a few songs and as a backup, I mainly play 6 string and wrote several songs that require 6 strings. I use DR Fat Beams in standard tuning, but unless they just recently released them, they don't come any heavier than a .125 set. For half step down, I would prefer to use a .130 set. Even if I stick with DR, there's enough variety to be confusing. I like a punchy string with some natural brightness to let harmonics ring out. I'm thinking either High Beams or DDTs will serve me well, but Sun Beams and Pure Blues also look good. Any experience with these sets? What would you use for 1/2 step down tuning?
I'm assuming you're using the FB6-30 set (30-125) for your 6? Do you like the feel of the other strings tuned down a 1/2 step? Because if so, you could but the FB5-30 set (45-65-85-105-130) and get a single .030 for the high C. Otherwise, the Hi-Beams would be the closest comparable set to what you're using.
How about the SS Lo-Riders? Their hex-core stiffness is better suited for down-tuning, but they're not quite as stiff as DDTs. And they do come in 30-45-65-85-105-130 as a factory set. https://www.drstrings.com/bass-lo-rider
After watching some comparison videos, I ordered a .30-.130 set of Lo-Riders. I don't think I could have made a bad decision going with a DR set, but these do seem to have a lot of traits that are advantageous for drop tuning while still having bright harmonic content.
I happen to have been playing the SS Lo-Rider 40-60-80-100-125 (standard tuning) on my son's Ibanez for the last few weeks and like their overall feel. Comfortable stiffness without ever feeling too loose or floppy. One size up for a half step down should work out fine.