This solution was devised by my co-op friend Healtti, I just made a video for it, providing explanation. This is a perfected method from the original one, posted by Dolla Bill30.
Get Unlimited XP with just mashing the A-button!- Mission 2: Gaberoun
- Cadet difficulty
- Have a dynamite in your loadout
Why this is the best way to do it? Because it doesn't require any attention, it's just button mashing, you can watch movies, live sports, etc... while doing this.
The rest is explained in the video. Enjoy!
I believe it is possible to turbo this on the Xbox 360, and One too, whenever a turbo-controller is available.
You will get these achievements too: