Nick, these days new doesn't mean the drums are correct or that they are even made correctly. Same goes for shoes.
I purchased AC Delco drums for another vehicle and had to have 1/4" of meat machined off of the outboard side of friction surface of the drum. The shoes were pressed up against "the curb" and wouldn't move.
In your third picture, it was the ridge where the friction surface meats the mounting surface.
Nick - I think Otto is onto something with his comment about the "curb" inside your drum. That may indicate the drum wasn't cut the full depth and when installed it's pressing against the outer lip of the shoe metal backings. First oc is yours showing the ridge. The other two are from vendors offering new replacements. There pics clearly show no ridge in that area.
Take a look at the other rear drum and compare the widths of the shoe contact faces. If your other drum doesn't have the ridge, or it's not as tall, try that drum in place of the stuck one and see if that allows for turning.
As Otto said, if you confirm the drum with the ridge is the problem, you can take it to a FLAPS or shop and have them turn that ridge down to restore proper clearance. If no one will turn it, next step is to purchase a new drum.
Let us know how it turns out.
