hmm, while i hope that they dont get mad for me quoting their page, and it being more of a offhand comment, i think this should clear some stuff up...
oh, and i kinda think that the double-tap with semiauto rifle is a kinda made up situation.
when bringing out a sniper rifle, you looking for a LONG shot. this would probably result in some range increments. now, stacking double-tap on top of that looks to me like a bad thing, unless your some kind of master sniper or something...