;D i thought by rolling it coz that would be difficult to control.. :
Lol nah. I think that previous weapon is set to mouse scrolling by default? its either previous weapon or simply scrolling through the weapons. Either way, i hated that. it was way to hard for me control. I would rather just reach my fingers to tap the numbered keys.
I normally switch to my pistol before I switch to my main gun in case I'm in a dire situation and hit q by instinct. I hate it when I sometimes forget and it switches me to a knife or a nade lol.