This legislation almost doesn’t do anything at all. And it says what the Illinois government thinks of you, a peon to be given occasional worthless indulgences.
Does anyone even make a rifle with a two-round magazine (magazine + chamber = 3 rounds max)?
At best this makes the rare double-barrelled rifle legal, or you could install a non-removable plug in a bolt action rifle. All made in the tight confines of the allowable ammunition.
Shotguns use a dowel in the tube to restrict the number of rounds one can load. The same could work for a tube-fed rifle.