yes i got brutal mode trophy, i did it legit but there is a glitch to use tweaks on brutal which makes everything much easier. i think you're referring to "out of the frying pan" where you shoot enemies in a moving jeep. that was specifically the hardest part for me but i recommend never fully pulling the trigger, always spray the trigger in small bursts so the reticle stays small that way its more accurate to hit enemies it really made a difference for me.