Frontier Justice

The Frontier Justice is the unlockable primary weapon available for the Engineer to be released with the Engineer Update. This shotgun cannot randomly crit and has half the magazine size of the regular shotgun, but can get Revenge Crits. For every kill your Sentry racks up upon it's destruction, the Frontier Justice gets 2 guaranteed crits. For every assist, it gets 1. This applies even if the Engineer destroys his own Sentry with the PDA.