If I recall correctly, the first reintorduction run ('77-ish or '79-'81) run of the BB featured machine and not hand engraved work. The engraving apears to be a bit shallower and linear in nature compared to subsequent hand engraved 'wiggle,' which were generally special run/Anniversary models (with marked interiors to identify the engraver). 

Click BB1 and BB2 below to see additional examples (they didn't insert for some reason???)

Cool!