Bolt on Eddystone 1917 wont chamber a round?

[Patrick Chadwick]

The way it looks to me, there is part of the neck of a casing stuck in the neck area of the chamber. Anybody else see this??

Could well be. Looks a bit sharp for the end of the neck section. The test I suggested is so simple that it should be tried first, before looking for special tools and speculating further.