[Twelvefield]

There's another AOB thread just a few below this one. It's not the easiest concept to deal with. More often than not, I just let the WO do the work nowadays.

But, have a look at that thread, and here's a good quote from it:

Originally Posted by Tombomsee

Try out this one :

http://www.communitymanuals.com/shii...e=Angle_on_bow

Lots of other helpful topics in there.