And the short method.
Just cut the barrel with a hack saw.
Slide a .223 cleaning rod through the old barrel so when it slides out the back of the receiver everything is held in place.
Then slide the new barrel over the cleaning rod and through the receiver.
It only takes about 20 minutes to remove the old barrel and install the new CMMG barrel/flash hider. Torque hider to 30-35 ft/lbs.