The difference that I am seeing between your stock and say the U15 or say the exile hammerhead is that it never drops below that line of the action.
Great idea but I am trying to flesh out the fixed stock "exemption"
So I am going to pretend I am arguing with the lawyers at my work, what if you designed it the same way but had it a 90 degree south from the grip then 180 degree east then north 90 degree for the buttpad (I will try to get a pic). That would be ridiculous, but would it qualify as a fixed rifle stock?
That example would blatantly show the web grip due to geometry.
On a design note, it is at A1/A2 length, is there consideration for the ability to cut some LOP off, say near a Sully stock length without hurting its strength or touching the receiver extension.
PS Thanks for innovating.