[Destructo6]

• 1) Put the buttstock against your sternum.
  2) Pull back the charging handle with both hands. It will can be very difficult to move.
  3) When the charging handle stops moving (it will only come back 1-2"), activate the bolt stop.
  4) While holding the bolt stop with your left hand, karate chop the charging handle with your right hand.
  5) Stuck round should drop free.

Haven't seen one yet that this method wouldn't free.

Try it out yourself:

• 1) Lock the bolt to the rear.
  2) Push the charging handle forward until it locks.
  3) Turn the rifle upside down, muzzle pointed up at about 45°.
  4) drop an empty case (or live, if you like) into the charging handle's concave bottom and allow it to slide back between the charging handle and bolt.
  5) insert loaded magazine into the gun.
  6) using the bolt stop/release, let the bolt slam home(-ish).
  7 You have just induced a bolt override [double feed (live round) or failure to eject (spent round)