This is, iirc, due to a bug with Sticky Grenades. When they stick to a target, they actually detonate twice. This is why stickies can cause mass collateral damage when stuck to a target. At least, that is the last I knew. That bug might have been fixed some time ago. On topic: Personally I agree that nano should effect head shots. Skilled players who can land consisant head shots will still have an advantage over players who cannot, but it would help to level the playing field just a bit. It would also provide an incentve to use Semi Auto Snipers over BASRs which are pretty much always superior. I don't believe "just don't get sniped" is a valid argument in a game where everyone can be a sniper and could literally be anywhere in a 360 degree battlefield. Though, I also believe some kind of indicator should be given as to what kind of armor a target is wearing. Say, you Q spot a target and they have an icon showing they have Nano, you could then either ready for followup shot, or engage a lesser armored target instead. It is a bit of a nasty suprise when a target survives what would normally be a instant kill due to their armor that they may or may not have but there was no way to tell they had it until you attacked. I kill tons of LA this way with my Flak Armored MAX after I survive a surprise C4. Or when you survive a rocket to the face with infantry Flak. If that heavy or LA knew beforehand that I had Flak, I doubt they would have engaged the same way.