Would fate really help? Ork's got like a zero percent chance of hitting, and a hit would kill. What would one do, anyway? Improving my odds to hit 10% doesn't seem like it would help.
Kannons have Blast 4, thinking back the blast conversation was on the other game. Blast means it has an AOE attack. Since missing with a Blast weapon means the projectile can go up to 5 meters away, kannons have a 4/5 chance to hit you on a miss. I kinda brought it up in the IC when one of the train shots managed to miss. This is what makes grenades good for low-skilled characters, you have a good chance of hitting even when you miss.
So your chance of survival are:
It jams. Not bad odds and you can probably make it to the wall and throw your grenade.
It fires, misses, and rolls a five. Now that you're close you could probably throw the grenade before they get the next shot off.
It fires, misses, and is far enough for you to dodge, and you manage your dodge roll. Fate would probably help here, either with the +10 or reroll.
It fires, you're in the explosion, and the roll just ends up really low. You have 11 wounds and explosions kill on ~8 crit wounds depending on location, so a 3d10+6-3 is survivable. Near 50/50 chance of instantly killing you depending on the location.
I thought I got the danger of kannons on infantry across in the writing but I guess not :-/.
The main way that Fate would help you is by burning it. Fate points act as mechanical plot armor. Without a fate point, there is a very good chance we'll get to see what a tradition knight's funeral looks like. If you burn a fate point, then you miraculously survive and the new Admech gets to replace whatever you lost with robot parts next logistics roll.