Sounds like it is working wonderfully for you. I would stick with the #6 if you are scoring better than 80 in the kill at 30yds. That is Awesome. I am somewhat surprised by these numbers with the factory choke. My factor choke was junk, and I shot absolutely everything through it to try to get better results. I trashed the factory one and went with the Kicks GT .690 and a BSA Red Dot. I'm getting 60+ in the kill at 40 yds and am perfectly pleased. At 20 yds, I honestly can't count because the pattern is too dense. The entire head turns yellow when using the Shoot N C target from birchwood.
Sounds like mine is not shooting any better than yours, even after spending $65.00 on my Kicks GT tube! If it aint broke...don't fix it.
Good Luck