I've had pretty good luck with accuracy so far. I use the iron sights, so aiming takes a little more skill. The rear sight is adjustable up, down, left and right. There is probably some variation in accuracy among the pellets as well. The scope that it comes with is a no-name cheaper scope.
I just wanted to throw out a warning about these. I have heard that these will beat the hell out of the rifling of the gun.
As far as a BB gun, that would not be strong enough. However, a pellet gun would. I picked up this recently...