Well, this is frustrating

[Derbeazle]

Deus Ex:HR, not Directors Cut. This is bound to be spoilerish, so be warned.
I'm on my second play-through trying for pacifist and I discovered that place where you can get a three shot P.E.P.S. gun. Amazing, I thought, this will be very useful in that place where there's hoards of opponents.
Except...
The freaking thing glitches back to single shot just when the crowds appear! I had saved before and after and reloaded to no effect.
So, is this a bug/feature, a glitch, or are they just screwing with us? Why u do this Eidos?
In other news; on my first play-through these guys were hitting me with no effect so I just waded through them. On this play-through OW, they hurt, what's up with that? Both sessions are on Tell Me a Story difficulty (I know, but I play for enjoyment, not stress).