Originally Posted by
cayugad
If you can remove the barrel, as sqezer said... Works. Or heat the area with a torch as a last resort, I have poured boiling water down a barrel, heating it. Wear gloves, then secure the barrel in a vice.
Please make sure its a padded vice or wrap a towel or something around the barrel.
You can also spray Liquid Wrench down the bore and on the breech itself. But I would try soaking in hot soapy water first and then get a socket on it and once you get it moving don't try to take it all out at once. Work it back and forth to get the grit out of the threads.
And next time put more antisieze on those threads.