I have to go with Borithan and Siranui here- with the base boltgun this seems pretty reasonable but when you throw in the Storm or Heavy in the mix, then stack on specialty ammo, then stack on talents, the multiplication takes off like a rocket.
Boltgun is S/3, but Storm is S/4/ Storm (so really 2/8). With the way these stack you can get into a place where a storm bolter actually does more to a horde than the heavy bolter with this addition (though I'm not up on the math of the likelhood, given that the Storm is in fact only semi-auto).
Yes, you have to be higher level to get things like SoI and to req Metal Storm or Hellfire rounds, but this goes back to my original point- I don't really like the idea that my players, with little prep or specialization in load out, can kill twice as many hordlings as they already can.
But with that all said, maybe they ARE taking all this into account and re-working the damage tables a third time. I wonder how many other surpsies are in there, hopefully not too many of the BC things I've heard of...then again, you can't please everyone all the time. I am one of the few people that actually liked the nerfed auto-pistols in hand to hand thing.