Submarauder inner robot

So after making a Bomb-Burst inner robot, I was inspired to turn my custom Fracture into Submarauder.
Just needed a new coat of paint and a new head.
Alt mode is the laziest mod yet - just turn it backwards for a "submarine", with a gun as a stinger. It's not the best but have you seen the original?
I've had a look at headmastering Skullgrin but can't see a way of doing it.

https://i.imgur.com/vdogDBR.jpg

https://i.imgur.com/aJldYNi.jpg

https://i.imgur.com/q27cE6P.jpg

https://i.imgur.com/O6wP4dT.jpg