No, I screwed up another entry from the books this time the Tech Level modifiers. Try number two:
Tech Level 7-8 down 3
Tech Level 9-10 down 5
Tech Level 11-12 down 6
Tech Level 13+ down 7
Medium Velocity Gun up 2
High Velocity Gun up 3
Tech Level 6 Hyper Velocity Gun up 4
Tech Level 7+ Hyper Velocity Gun no mod
I understand this set of result as consistent, but I still have a confusion (with what the rules say maybe more than what you wrote):
So, the table is for TL-6 mortars/low vel guns.
So when I get increasing TLs, I count 'down' the table (towards higher Pen values). That makes sense.
Then we see modifiers for gun type (Medium up 2, Heavy up 3, Hyper vel up 4 at TL 6, then nothing at TL7
So...
1) If counting down takes you to the higher penetrations (as you'd expect with TL increases), why does a medium gun count, then heavy, then a hypervel count UP farther each gradation? Shouldn't they count DOWN as well? Does penetration decline by medium, heavy, hypervel? Why?
2) If the rules of physics are what they are for TL6, why does the TL 7 one get no changes?
You end up with (based on gun type):
Medium Gun (any TL) - count up (to smaller penetrations?)