I don't think vent liners come in a diameter large enough for that Slowburn. Also, they have a hole completely through them. I didn't want that.

There is another barrel mounting option though. That would be to use a long " full thread" bolt screwed one inch into the breech then cut off, leaving one inch of bolt sticking out the rear of the barrel. Then the breech block could be drilled and threaded to receive that bolt, and the barrel screwed into the block.