Last shot at a problem. Call and/or contact by e-mail, individual barrel makers, Numrich Arms, Dixie and ask if they have any blanks, in stock or new-old stock in the back, that have been bored to .540 (or close,) but haven't yet been fully finished or rifled yet. I've managed to get stock blanks for some of my CF projects faster, because I wasn't waiting in the 'same' line to get all of the 'finishing touches.' Saved a tiny bit of cash too. Just a thought. I'm all-in and well done... stick a fork in me.