The Constitution is an ever-evolving document. Amendments are made according to changing times and progress. The right to bear arms to defend yourself against enemies is now obsolete. It belonged to a different era and a different social setup. We have no enemies here. They are thousands of miles away and do not have the capability to reach our shores.
And if by “enemies” you mean thieves and robbers, you don’t need military-grade automatic weapons to kill an intruder in your back yard, unless you are a poor shot with your shotgun. Likewise, you don’t need an AK-47 to shoot down ducks.
However, the sad fact of the matter is not about the right to defend yourself against enemies, but against loss of business in automatic weapons.