I was not very excited with my sample of Nightshade, out of my pens it appeared more of a grayed brown, very little red showed on the paper once the ink dried. However, adding a bit of Shah's Rose and Saguaro Wine made it a lot better.
I haven't seen old Shaeffer's Burgundy, so can't speak to that.
I spent a fair amount of time playing with making my own mix for burgundy, and came up with several. None of them too exact I'm afraid, as it seems my drops (basic measuring unit) were not very consistent in volume. But in general, by starting with a red similar to Shah's Rose or Diamine Amaranth (slightly cool/bluish) , and adding either Diamine Woodland Green or PR Sherwood Green (both are cool greens) at a ratio of about 3:1 or 4:1, you will get a nice, subdued burgundy color that will shade.
6 Shah's Rose to 1 ebony green also works, as does 6 Amaranth to 1 Aurora Black (or probably any other black).
It turns out that my burgundy is very similar to the FPN Tulip Noire scan shown here:
http://www.fountainpennetwork.com/forum/in...mp;#entry405557The theory behind this is that red and green are opposite on the color wheel, so they mute each other. With a cool red and a cool green, they share the blue component, and with red dominant in the mix, it will trend toward purple. If you used a warm red (toward orange) it would lean more toward brown. In fact, if you want a more neutral (brownish) hue, just add a tiny bit of yellow.
These are all fairly subtle (not bright) shades of burgundy, but by adding a little more of this or that, they can be tuned pretty easily.
I used tiny plastic cups, and started with 4 drops of the base color, then added the other color a drop at a time, sampling after each drop, using a fountain pen nib inserted into a dip pen to test the color. Color from a nib on paper is a much more accurate representation of what the ink will look like in writing, than from a swab.
Edit: I played around with both photo's and scans, but even after processing in Photoshop, can't get a realistic rendition of my burgundy, so I give up on that.
Dan