There are two versions of the Gunroom archives:
The hmssurprise.org internal archives This is a searchable Hyperkitty archive, going back to very near the start of the list in October 1995. You will need to be a member of the list to visit the archive and will have to sign in to view it. List members can also post new messages from here. Gunroom subscribers who were moved to the latest version of the list automatically from the previous one will have to create a user ID and password to view and post from the archives.
Michael Trick's Gunroom archives This is an external site, which has another searchable version of the archives (searchable only up to 2018). It also goes back to October 1995.