My understanding is the action is designed that if it's not locked up right, it won't fire. I suggest taking the locking lug(s) out of one of the barrels that work, and swap them into the Hornet barrel. If it works after that, you'll know it wasn't closing fully, and you will have to stone the origional lugs, or replace them. I remember having to swap lugs around years ago for my brother, but don't specifically remember why. At any rate, this is an easy test.