I run Engineer and buff my gun and use the rifles.
I use the other one, not the Drognov, or whatever, but if I buff my gun with Engineer, I get quite a few One Hit Kills, because a lot of people are injured.
Anyways, I wish you could should it a 'little' bit faster. Its quite un-reasonable.
I'm personally pleased at the lack of quick scoping, as it was a constant drag when playing MW2 and likes. Thankfully they've given it a mirror's edge feel to the game play, so I'm pleased. I loved that game!
Hip fire, not so much, but I've used them scoped at point blank very effectively. They did them right though. It takes some manual dexterity to land good shots, but I've found them no more and no less accurate so long as I'm scoped in and on Target.
It's call quickscoping... And it's not that hard to do in this game. The Barnett acts a little weird sometimes but nothing too bad. Not good for playing objectively but good for messing around in solo.