Reading this thread is painful.
In my years of running a shop, things stuck in barrels, with the misery compounded by ill advised attempts to dislodge them, were some of the greatest challenges.
There have been some good suggestions.
Kroil is a superior product.
There have been some really, really bad ones.
Here is a method that should work, and will not do any harm if it doesn't.
You will need a short piece of rod that will just barely slip into the muzzle. Brass would be fine. A short piece of dowel would actually be OK if used only for this method. It must be a tight slip fit.
Fill the bore with oil, almost to the muzzle. Start your plunger into the bore. Give it a good, sharp rap with a hammer. The hydraulic pressure should pop out the case. There will be a mess. Obviously, you will have to plug the gas port.
If you want to try hammering the case out, you want a piece of smooth steel rod of the largest diameter that will just clear the case neck. A piece of O-1 or W-1 drill rod would be ideal. It is available in many diameters. Cut the rod so that only a couple of inches project from the muzzle.
A good crack with a fairly heavy hammer should do the job.
Stop, take a deep breath, and take the time to get the proper tools.
Try the hydraulic method first.
Incidentally, the hydraulic method is a really good way of removing stuck live rounds. First hit will drive the bullet back into the case, and flood the powder. Top up the bore, and the second hit will expell the mess.