I have a "new" pen I would recommend, especially for copperplate.
I just received a box of Eagle E470 "Magnum Elastic" nibs. I've not purchased this Eagle number before, and I figured with that name they were worth a gamble. I paid $26 for pretty much a full gross of them. That helped too.
These remind me a lot of Esterbrook's 453 Business and College pens. IAMPETH lists the 453 as good for copperplate. The E470 is at least as flexible with good snap and a fine line. It share's the 453's problem of not fitting in standard oblique holders. This is not a small nib, but for straight holders, it's quite a good, flexible and durable nib. It's essentially the larger version of the Eagle E370 College. The E370 does fit into oblique holders and is quite flexible. This E470 is larger and will last a long time, and seems better suited to straight holders.
With walnut ink on good paper I was able to get .5mm hairlines and a flex up to 3.2mm with reasonable pressure. With good control you can write decently in 9mm lines, and very well with larger size letters.
This is my poor writing in a 9mm-line Black n' Red notebook. I did not get even close to pushing it for this example. I easily wrote quite well with my letters twice as large.
I've not noticed this Eagle pen before, but that doesn't mean it's not periodically available.