MegaSearch isn't just for searching content, but also a fine newsgroup browser.
Just type the name of your newsgroup (or a part of it) in the 'Newsgroups Field' and leave the other search fields empty.
That way you get all the postings from the newsgroup.
With the previous/next button at the bottom your can walk through the pages.
Browsing newsgroups
Browsing newsgroups
If you like Usenetic, please give it 5 stars at MacUpdate: https://www.macupdate.com/app/mac/59624/usenetic