There are no semi-automatic assault weapons.
Assault weapons are weapons needed to attack a prepared defense. Accuracy, lightweight, and durability are not important for assault weapons, but a high rate of fire is.
There are no assault weapons. There are assault RIFLES, the correct definition to include select-fire capabilities, meaning full-auto or semi-auto at the flick of a switch.
An "assault weapon" is anything that is or can be used in an assault, which pretty much includes everything, even handfuls of sand.
/soapbox