I get it, but i'm not sure why... I've never heard of anyone referencing the outside of the group as the group size.
For field target Troyer rating the diameter of a pellet should be accounted for in the calculations but it is too complicated to have a different Troyer rating for the three calibers. This is the one use case where I see Caliber MOA being a thing (shooting through a small hole). But its fairly unique to field target.
"As such, my standard for edge to edge five round group size when testing pellets became 0.0324" plus caliber, or what I call Caliber MOA."
So really your "Caliber MOA" group size is 0.2094", it does not make a lot of sense to say "Caliber MOA" and call out a center to center dimension (which is a non-caliber MOA way of calculating the group size).
What are you using this calculation for?
Center to Center group size is widest point Edge to Edge minus the outside diameter of the unshot projectile punching the hole.
The world record for a Center Fire 30 caliber five round group at 100 yards is 0.0077" Center to Center.
I keep hearing how accurate PCP rifles have become and I laugh because a 30 caliber PCP rifle is not capable of a five round group of 0.0077" Center to Center at 20 yards let alone at 100 yards.
My sub 12 Ft-lbs 0.177 caliber Thomas Precision Benchrest rifle routinely produces 5 round groups of < 0.2094" Indoors at 20 yards so to be fare to my 0.30 caliber M3, I am just scaling up the group size relative to the 0.177, which is the 20 yard MOA minus 0.177 and adding the difference to 0.30"
As for the AAFTA Troyer:
A. At 20 yards the smallest KZ diameter allowed is 0.5" having a Troyer of 40.0. This KZ is 1.50" times greater than my Caliber MOA Standard of 0.3324" EtoE for a 30 cal. .
B. At 32 yards the smallest KZ diameter allowed is 0.75" having a Troyer of 42.7. This KZ is 2.256 times greater than my Caliber MOA Standard of 0.3324" EtoE for a 30 cal.
C. At best the Troyer regulated KZ sizes are a measure of accuracy but in no way are a measure of precision.
D. I call it Caliber MOA and define it as 0.0324" + projectile caliber because it is my standard.