Not luck - you are a good millipede keeper! That is crazy how long they are. What I have now are Sonoran Chocolate and they aren't as long as the Golds I had a few years ago. I never measured them but I would guess a few were around 8".I have at least two ornatus out of my bunch that are 8"+. It is crazy! When I got them they were already a good 6" and I assumed they were full grown. I kept expecting to start losing them shortly due to old age, but I haven't lost a single one and they just keep growing. I just consider myself lucky!
Maybe you will break the mold and be a Oo champion! We can certainly hope for that!@mickiem The ones I'm talking about are the Reds. They are longer than my Golds, and those are pretty long themselves. Most likely full grown. I catch the Reds mating all the time. I keep waiting for babies to pop up, but I know that's not likely to happen.