The Continental Army was formed in 1775, after the start of the Revolutionary War. It was mostly disbanded in 1783 after the war ended. The remaining units formed the Legion of the United States in 1792, from which sprang the United States Army in 1796.
The Second Amendment was ratified in 1791, after the war ended and the Continental Army was disbanded, and before the U.S. Army was formed. It was needed at that time since there was no formal military body to protect the US citizenry. In my opinion, it became unnecessary once the U.S. Army (including National Guard), and formal police forces were formed.
I won't argue the merits of the Second Amendment, since it provides legal basis for private gun ownership. But I see NO logical reason for private ownership of military-style assault weapons. They're an overkill for defense of one’s home, and they're inappropriate for hunting. Their only use, then, is for mass killing of other civilians, which is TOTALLY unjustifiable.
Disclaimer: As submitted to the Arizona Daily Star.