The following achievement's task of assassinating Jasper Knight with a sabotaged ejector seat should net you a ballistic and accidental kill.
The death was due to a projectile, the seat, and was conditioned to look accidental. For an explosive kill, go the the Freeform tutorial. A remote detonation device can be found in front of where you spawn along with some coins and a lock picking tool. Use it to net an explosive kill on your target. Once you have successfully performed all a ballistic, accidental and explosive assassination, you'll unlock the achievement.