DMR aims for you, has a greater bullet magnetism and a faster fire rate. I call it the DNR, Designated Noob Rifle.
As for adjusting your sensitivity to 2, screw that noise, I play at 6 now and feel like I turn to slow. When I started having a tough time with my aim I do the exact opposite of what has been suggested, I adjust up for a few matches than slowly bring it back down until it feels right.
Never forget that no matter how good you get with the BR there will always he someone with DMR and a sensitivity of 2 who will kill you by spamming the trigger.