Read the law. It's simple. To be an assault weapon, the rifle must have a detatchable magazine AND ONE of the following characteristics:
Pistol grip
Bayonette lug
Flash surpressor
Collapsable or folding stock
As long as you load no more than 7 rounds in the mag, you are good to go.
So, the law as wriiten, means Saigas do not need to be registered. Also, SKSs, dispite having a bayonette, are still legal due to the fact that they do not have a detatchable magazine. (if left in original configuration, of course)