actually you can have a monsterman style grip or a u-15 stock (both pictured in the previously posted assault weapon id flowcharts and have a 30 rounder if you have a perm attached MUZZLE break (not a flash hider) or a plain non threaded barrel and a fixed stock. you can have detachable 30 rounders all day long (if you had prior to 2000)well, said.
this is the only part thats mine. the rest of the post was from someone else above