Dang!
I presume you mean the shoulder stock is illegal.
Which gulag do you live in?
Nope, in Michigan, pellet guns .177 and over with rifled barrels are considered firearms by the state. A pellet pistol has to be purchased with a permit and registered in accordance to state handgun laws. Also, since they're "firearms" they cannot be equipped with a devise the alters the report. The Marauder rifle and pistol have shrouded barrels making them illegal no matter what their length. Stupid, eh?