I highly doubt the issue is duds included in the modeling.
I rather think it's a specific angle/speed/range combination that returns a variable damage number that doesn't induce damage.
Call it a fluke and move on.
If anyone is willing, I'll gladly go to the DA to research and send an email to HiTech saying "Hey Dale, check this out- if you're attacking a spitfire 16, doing 250mph, he's doing 200, and you hit him with a tater in the wing root at an AOT of 45, with his wings rolled 90 degrees, damage that should be happening is not."
That's really the ONLY way we're EVER gonna isolate this. The data is being sent and received just fine. It's the math in the middle yielding a weird result (my personal bet would be a neverending whole rather then a decimal figure) that throws the DM for a loop, and says "You scratched his paint, nothing more."