Thought I would share something I learned today. Maybe this isn't news to most. I've been going after siege for like two weeks now on default settings. I always read and thought you could hit the doors and then the Walker for a jackpot. Been trying to do this for this whole time. I noticed today after my third prison mb in a game that regardless of how many times I hit the doors, they wouldn't open. Took the glass off and discovered after 6 kills, hitting the doors doesn't open them. You have to hit a ramp and then hit the prison. There really isn't an audio cue with cleland code to tell you you got a jackpot once you start alternating ramps and prison besides the shaker (if you have it).
Hopefully with this information I can finally attain it. After I do, it's definitely going down to something like 8 jackpots instead of 12 (I have a pro)