Greg did you retain copyright of your articles that Hundman published? If not, and you were compensated, they are most likely the property of the publisher, and by transfer, thus property of the C&OHS.
While I did not write anything for Hundman, and do not know his author agreements, I did write for Railroad Model Craftsman when published by Carstens Publications INC. I recall the checks from Carstens had a clause on the back stating when I endorsed the check (ie to cash/deposit) I was signing over ownership of the article. This meant Carstens could do anything they wanted, including reprinting/publishing, and I could not prevent them. At the time Bill Schaumburg advised me to retain copyright of my material by including a copyright notation on all work submitted. This permits me to use my work as I wish.
I think this practice is pretty standard in the publishing world. I undertand Kalmbach "buys" articles, and sometimes they sit for years before getting published, if ever. By paying for the article, Kalmbach becomes the owner and the author is prevented from publishing elsewhere.
Perhaps someone in the publishing industry or legal field can speak more directly to this matter. But if you did not retain copyright, you may not have control over material Hundman Publishing printed. That is my understanding.