Bunker Grenade launcher question

If Bunker rolls a 6, 5, 5 on grenade what happens?  Does he just damage himself?  Does he damage 3 enemies and himself, or damage 2 enemies and himself? 

My impression is that if he rolls a double the the attack fails and instead of attacking he either takes damage or a twist

Because the self damage clause doesn’t say “instead”, I would say it sounds like you still get the full normal effect in addition to the twist/self damage. Like, you’re firing off more than three grenades and one happens to land close to you.

This is correct.