a de-facto ban on all semi autos would be due to ATF's enforcement of this bill due to vague wording. Not a bill passing that explicitly banned all semi-automatic functioning firearms.
"any part or combination of parts that is designed and functions to increase the rate of fire of a semiautomatic rifle"
covers>trigger / trigger groups>BCGs>buffer tubes>gas systems>magazines
Worse is that "increase" is a relative term. Increase from what? 10 rounds per minute? 1 round per minute? If you make that interpretation, it covers any semi-automatic functionining firearm