Getting a natural attack to scale with size

[burkoJames]

I am working on getting the Strength Devotion feat from Complete Champion fully working. im starting on getting the natural attack to work properly

I can bootstrap wSlam in. Apply the Tag 'NatPrimary' in group 'Helper' to get full strength bonus.
For damage i pulled up the code i get when generating a weapon and find that '1d10_304' in wMain is the correct tag. It all works.

Except when the character then uses enlarge person. the attack doesn't then scale to the next step.

Any ideas?