A 16 or 20 gauge semi-auto shotgun with plastic furniture is actually a great starter gun for a kid. I know many folks that teach their kids to hunt water-fowl for food with a 20 gauge semi-auto shotgun. If money is no object, you can get them as light as 5lbs (~2.26 KG) but most would be in the 6-7 lbs (2.5-3KG) range.