There were several 'BAN' versions of the AR rifles made also. One was made a pump rifle that kept all the AR bolt, bolt carrier, recoil springs, buffer, ect.
They just added a pump sleeve to unlock and cycle the bolt.
And there is a left handed straight pull bolt versions of the AR to beat the last ban.
It was simply a slot cut in the upper receiver on the left side, and a bolt handle screwed into the bolt carrier.
The gas tube was removed so make it a 'MANUAL ACTION'.
This actually works quite well since your left hand is often doing nothing, and you can fire quite quickly from a rested position.
The 'PUMP' AK's had to be purpose built, while existing AR's could be retro fitted fairly easily when they came looking for 'Assault Rifles' on the 'Left Coast'.