Ever since the Black Armory patch (from 11/27) the animation cancelling for reloading doesn't work. Prior to this update you could cancel your reload animation by sprinting early and begin firing your weapon immediately after the weapon displayed having bullets in the clip (this was very useful for incredibly slow reload speed weapons).
With the new update you can still cancel the animation early and bullets will still be in the clip, however your weapon will not fire until the point at which the animation would have ended.
My "Bite of the Fox" has a very slow reload speed (extended mag does that).
Reload animation lasts ~5 seconds.
Bullets are loaded into the clip after ~2.5 seconds of the animation (UI shows 5 bullets loaded).
If you cancel the animation right after this, the gun will not fire for an additional ~2.5 seconds.
I'm not sure if this fixed a bug that allowed players to ready their weapon earlier than intended, however if this was intentional it would be nice if the UI didn't show that the gun was loaded until the animation ends. I'm a big fan of the animation canceling technique because it's a skill based mechanic. If you cancel too early you have to go through 2 reload animations. If you time it right, you're able to gain an advantage compared to someone that doesn't time their animation cancel correctly.