I noiticed that QBS-09 (Brown Army shootgun) when taken into inventory is counted only as 10% of backpack capacity. Not sure if this is bug, or fully planned feature, however AFAIK every not-rare weapon was supposed to take more than 100% of backpack capacity (and in consequence forcing player to have reduced aim while holding such weapon in inventory).

oooh totally forgot to fix that, though I wrote it down a while back. Thanks, gonna be fixed in 0.98.