Gun Control & Minimum age

Gun control had been a problem for a long time. Two of the big problem are the lack of background checks and the minimum age for buying a gun. As stated in the article, one study by researcher at Northeastern University and Harvard University estimated that 22% of gun sale occur without a background check”, some gun sale doesn’t require background check to buy a gun. The minimum age to buy a handgun compare to a Ar-15 is non sense too. You need to be 21 to buy a handgun, but you can get a shotgun at 18?