Generally speaking, one can only shoot ONE assault rifle at a time - at least with any accuracy. Having more long guns or assault rifles “available” does not alter this fact.
However, having an armed populace that can shoot back can drastically change the out come of this type of assault.
https://www.youtube.com/watch?v=qzMx3Z5EbQQ
"Infidel! You lie! Even now our terrorists are learning to shoot you with our feet as well!"