Tonight while searching halves I found a 1979 half that was noticeably smaller than the other halves in the roll. It also weighed about 1 gram less. The edge still has a nice reed so it wasn't purposely made smaller.
I checked eBay and didn't see anything similar, so then I went to Google. The only thing I found was an article about half dollars that were struck on Susan B. Anthony planchets in 1979 and 1980 (maybe other years too). Here is that article:
http://www.numismaster.com/ta/numis/Article.jsp?ad=article&ArticleId=4741
Any light that can be shed on this would be greatly appreciated. Here is my small 1979 half dollar:
Thanks, Nick