OP 2nd amendment guarantees my right to own a semi-automatic weapon.

No it doesn't - you still have pistols, rifles, and shot guns**.. in the late 1920s and early 1930s we banned machine guns because mobsters were using them to killpeople... . We outlawed hand grenades... can't get em. So what's the difference with semi-automatics and mega clips? Nothing ! There are limits to your rights ! example: 1st Amendment- can't yell "FIRE!" in a theater. **With the 3 above - anyone's 2nd Amendment rights ARE still preserved.
David (OFI)