If you are using a hand held barcode scanner or wand, I'd hold that in the left hand; you can do all numeric entry with your right hand.  Refer back to the 'data entry cheat sheet' for my suggestions on data entry.

It doesn't matter whether the data entry screen is set to display shooters by name or shooter number or division or squad.

It also doesn't matter whether you've selected Shooter or Stage entry mode.

 

You can also scan barcodes when you've selected Direct entry mode.  This is more efficient, because the list of shooters' scores does not need to refresh itself after each stage you enter.