I tried a Gunslinger engineer build and was using Frontier Justice. I would drop my combat sentries in locations where they seemed really likely to destroyed thinking I would get bonus crits.
However, I was having a bad night (or perhaps all my opponents were having really excellent night) and I was dying too frequently to see if I was even getting the bonus crits. Does anyone know if this works?
It most definitely works. This is my new preferred way to play my engineer. You can keep track of the # of revenge crits you have racked up in the bottom right corner of the default interface above the ammo counter. One of the nice advantages of using the mini-sentries with the Frontier Justice is the ability to blow up your sentry intentionally to get the crits, since rebuilding mini-sentries is quick and cheap. It's an effective way to provide your team with additional offensive prowess: critical shotgun shots do a significant amount of damage.
Keep in mind that you get 2 per kill, 1 per assist, and your mini sentry is much more likely to get an assist than a kill due to it's lower damage output.
The frontier justice does not care what kind of sentry you have, though it might be harder for your mini-sentry to get kills in the first place.
