Carbon Outlaw, on the loose barrel it looks like the chamber is OK? That is for demo purposes, correct?
The barreled action does look like the case is sitting proud. If it were mine I would try an EMPTY case with black Sharpie marks all over and barely tap it in a little, then tap it out through the barrel. It does not need to be forced, just get it stuck a couple of times so you can tap it out with your palm. I would expect that you will see the marks on the brass were your interference is coming from.
If it is actually not finished reamed it could be finished by hand without unscrewing the barrel. See the last item or 2 in my thread:
(You need to Login to view media files and links)If you can borrow or rent a Krag standard reamer you can use my brass extension to drive it. My reamer is 35/40 and I just sold it to a fellow KCA member who is building a sporter with a 20 inch barrel. He is supposed to be taking pictures to share here later.
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There is a possibility you just have some dry crud stuck or glued in the chamber, if so you could hack saw and file a case in half and use it like a "cleaner" reamer, just need a way to rotate it. If you put 1/4 -28 threads through the primer hole my driver could be used to turn it.
Would sure hate to see you stop on your project.