lol I know its confusing to me too I would love to send a picture of the barrel and make it easier. The best way I can put it is that the barrel has a spiral but there are no groves that I can see. I am going to take it to the closest gunsmith as soon as I can and see what he says about it.
The Mdl. 67 "Boy's Rifle" was made in a smooth bore and a miniature target grade. The Miniture Target Grade 1942 had a 24" barrel and bead sights the same as the famous Winchester Mdl. 12 shotgun.
There were some 300,000 of these inexpensive single shots made from 1937 until 1963. They sell for around $200 dollars in the rifled version.