Well, long ago, in a galaxy far, far away, there was a strange device called a "boy's rifle". Seems that folks actually sold firearms that were made to be used by a child. In some cases, they were sent thru the mail as a reward for the child selling stuff door to door- like Clover brand salve.
Perhaps the most common were the Quackenbush, and the Hamilton. Some had a sheet metal or brass barrel, with a thin steel liner. There was even a version known as a "Bicycle rifle". Imagine, letting an infant ride a bicycle with a firearm- and no helmet!
Foregoing WAS sarcasm for those that missed it
Here is a link to some of the Hamilton rifles- nice photos. Also Google Quackenbush guns- you can find an image of the book just published, with nice photos on the cover. Wesson Arms also made a "bicycle rifle".