I am playing Dark heresy (1st) with my group. Because for the upcoming mission weight in a limiting factor, the players came up with the idea to attach the extra grip (pistol grip) to their weapons. This way the weight of the weapon is reduced to just 1/3 and the weapons can be fired with one hand without a penalty, for just the cost of halfing the range (which, honestly isnt that bad with most weapons). In addition, if you hold the weapon with both hands you have the original range (as per errata). For me it appears as if the upgrade has no real disadvantage or some king of trade off (like with the compact upgrade) what seems strange for me.
Th question ist: is the weight a typo or is it intended to reduce the weight in such a drastic manner? Adding 1/3 kg would make much more sense to me.
And if it is (because RAW it is, unless i have overseen an errata) how do you loose so much weight on a weapon ? And, most important, how would you handle this in your group?