I wish I could understand the logic behind wanting unlimited, unregulated and undocumented access to any gun imaginable along with the unwillingness to take responsibility for said guns.
Rights come with responsibilities.
As for what a 16 and 17 year oldcare capable of understandings, of course they are, but their brains are immature and their ability to evaluate risk isn't fully developed.
Our legal system gives people until 18 to mess up with less consequences.
It protects society and children by limiting access to certain things until certain ages.
Just like the adults who supply minors with alcohol, those that supply children with guns should have some culpability in the outcome.