I'm restoring an old 1850 Mansard style home. On the third floor, all
the windows are original but the hardware has long since disappeared.
Since the dormer style of the mansard did not allow for the use of
"sash pulley and weights", the barrel type loc/stop is used. I
actually have a few of these still laying around, except they are
broken and I cannot use them. Here is an example of what I'm looking
for: http://www.eddonaldson.com/wnd7.htm#Reference%20%20640-540
Notice on the page the Babcock barrel type sash lock, it is exactly
what I need but have not been able to find. Looked on e-Bay and around
the web. It seems Ed is the only one to have them but he is sold out.
Anyone know of where I can get replacements or possibly more
information of this type of window hardware? Im at a loss, please help!

Is this any good?

http://www.houseofantiquehardware.com/rehdw_window.htm?r=GAwinh

Thanks for posting. I have seen the hardware they offer, but they do
not have something like the barrel type. They and other sell "pins"
and tension springs, but these are no applicable to the current setup.

I'm not sure if they have it in their catalog, but Blaine Window
Hardware - http://www.blainewindow.com/ - probably has it, or will
make it for you if you send them a sample.  They're good folks!