I've got a couple of extended chokes for my SBEII that don't fit flush at the barrel/choke junction at the end of the barrel. Where they do fit flush is inside the barrel, the choke fits tight against the barrel skirt. From what I've seen, it's normal. It seems they machine them a tad long, to ensure they fit tight inside the barrel, where it matters. That choke might be fine. It could also be swelled too. I'm just relaying my experiences.