It’s strange that the research cited here isn’t also used to support withholding free speech, due process and voting rights as well. Why take any chances?
There are developmental reasons people in their late teens and early 20s, especially males, are particularly likely to engage in gun violence and other dangerous acts (like my reckless driving). A crucial factor is that the frontal lobes — which help us think through our actions — do not fully mature until roughly age 25. There is, moreover, another brain-development issue relevant to mass shootings in particular: The teens and early 20s are a crucial window for the onset of severe mental illness, particularly psychotic disorders such as schizophrenia. That window begins to close around age 25.
These facts open the door to a gun-regulation compromise. Even if more aggressive measures are stymied by gridlock, Congress might consider banning the sale of firearms to people under 25 (except, perhaps, hunting rifles). Even conservatives have shown some appetite for age-based restrictions: Just three weeks after the shooting in Parkland, the then-governor of Florida, Republican Rick Scott — now in the U.S. Senate — signed a bill shifting the age for purchasing a firearm from 18 to 21. But the choice of 21 was arbitrary. Recent research in neuroscience suggests that 25 makes more sense. …
Several businesses whose profits depend on the safe use of their services recognize the risk posed by people in their late teens and early 20s. For decades, insurance companies have charged young drivers and their parents high fees because they are responsible for a disproportionate share of accidents. Most car-rental companies refuse to serve people under 25.
— Drew Westen in You shouldn’t have a gun until you are 25, research suggests.