Try calling NEF ( New England Firearms).
265 Industrial Rowe
Gardner, MA 01440
Phone (978)632-9393
Fax (978)632-2300
That should give you a lead. I'm not exactly sure of the relationship between NEF and H&R as in whether they just bought the tooling from and H&R after they went under or whether they took over the complete operation, including the books.
You could also check this site. It gives dates of production on a couple H&R handguns.
http://www.gunsworld.com/gun_revolvers.htm
Good SHooting
RED