here's what I think
I have not done any pattern measuring w/ 00 buck, but have shot and seem quite a bit shot, at LE quals.
I believe your gun is shooting exceptionally tight w/ the 2 3/4" loads, and the 3" loads are performing more like the norm.
Seems like a read/heard the standard for Cylinder chokes was 1" spread for each foot from the muzzle w/ buck. That's not gospel, just an observation and if I read your tables right, that's about what you've got.
Well done on patterning your gun.........& w/ differnt loads no less.
Now you know.