Has anyone come across a fake of a non-existent factory model? Something that has been crafted to look like a factory job but isn't?

Like if someone got hold of a BSA Meteor Cadet and made a faux SLR (FN FAL) trainer out of it, like the Rossi Sport 82 or EB79, and then claimed that it came out of BSA but as it was not commercially available there was no mention in the Press about it, and only a few were made and were rejected by the MoD. So no paper trail and 'it's worth £1500'.

Well, did it happen?