Note that Eddystone barrels were installed with machinery and some are very tight. When the barrel is not going to be salvaged, the gunsmith should make a relief cut just ahead of the receiver to prevent receiver cracking when the old barrel is removed.
That is just one reason why I second Dfariswheel's comment about the "corner gun tinkerer."
The factory made the extractor cut before installing the barrel by using a special gauge that made a "witness mark" or draw line to use as a reference point. Since the gunsmith doesn't have that tool, he has to install the barrel, mark it for the cut, then remove it, make the cut and reinstall. That takes time and raises the cost, but there is no other way to do it.
Jim