Any stock that makes a gun bullpup is illegal. Bullpups are only legal if the gun can only operate in that configuration. Since 10/22s and 597s can be fired conventionally and CBS stocks are just drop in/add on it, it is illegal.
PART 4
PROHIBITED DEVICES
Former Prohibited Weapons Order, No. 9
2. Any rifle, shotgun or carbine stock of the type known as the “bull-pup” design, being a stock that, when combined with a firearm, reduces the overall length of the firearm such that a substantial part of the reloading action or the magazine-well is located behind the trigger of the firearm when it is held in the normal firing position.