Also all my drill rounds are stamped SX 1030 where as all my other 105s have different SX numbers I have also been told by some experts on shells that they did re purpose HE etc shells to be drill shells this is when you see the SX number has been stamped out and changer to SX1035Fired bands can be deceptive as the copper is deformed by the lands and fills the grooves giving a larger diameter after firing than before, albeit not by much. Sounds like your drills have different bands to a service shell though, which makes sense.