Try shooting your BHs a little longer. I had a similar problem, But the more I shot them, they came more on target. IMO, I think there is a mental thing going on when you 1st switch to BHs. (Newbies Problem) I don' t know if it' s " peeking" or " Guiding" but something goes on. Shoot ' em and if they stay constant low left then move your sight.
Good Luck