despite the fact that emp grenades should stun robots and androids for two turns according to the wiki, the machina fight for the zk rifle seems to be an exception to this. i have thrown multiple emp grenades and i have not stunned the bot a single time. speaking of the machina fight, i could have sworn there was a time you could avoid the fight altogether by sneaking up on the bot or something and turning it off, and that there was unique dialogue where carl commented on the fact that the machina was completely undamaged.