I'll start it off, and I will update this list as they come in:
www.ar15.com
www.ak-47.net
www.hk91.com
www.glocktalk.com
assaultweb.net
www.hkpro.com
www.subguns.com
pub33.ezboard.com/bfirearmsfriendsfamily
fnhipower.com/wforum/index.php3?bn=fnhp_fnhipower
forums.forthehunt.com/cgi-bin/ubb/Ultimate.cgi?action=intro
www.geocities.com/CapitolHill/Lobby/1221/guns.htm
www.ktog.org/cgi-bin/ubb/Ultimate.cgi?action=intro&BypassCookie=true
www.benchrest.com/
www.hk91.com
WWW.SNIPERCOUNTRY.COM
www.gunsnet.net/forums/ruger/cgi-bin/Ultimate.cgi?action=intro&BypassCookie=true
www.unitedforums.com/cgi-bin/wfcgi/Ultimate.cgi
www.wetworx.com/~wetworx/cgi-bin/Ultimate.cgi
www.weaponforums.com/
www.waffen-online.de/cgi-local/Ultimate.cgi
www.ugw.org./ugw-mb/board.html
www.unitedforums.com/cgi-bin/ufcgi/Ulwww.unitedforums.com/cgi-bin/tfcgi/Ultimate.cgi
www.prebanguns.com/wwwboard2/wwwboard.html
kalashnikov.guns.ru/wwwboard/board2pub7.ezboard.com/bsurvivorssksboards.html
pub11.ezboard.com/far15discussiongeneraldiscussion
subguns.biggerhammer.net/gunrelated.cgi
www.sturmgewehr.com/
www.stg-58.com/cgi-bin/stg58cgi/Ultimate.cgi
www.unitedforums.com/cgi-bin/steyrfcgi/Ultimate.cgi
www.steyr-aug.com/boards.htm
www.smith-wessonforum.com/cgi-bin/sandwcgi/Ultimate.cgi
kalashnikov.guns.ru/wwwboard/board3/
www.sigforum.com/cgi-bin/cgiwrap/sigforum/Ultimate.cgi?action=intro
www.shooterstalk.com/
www.unitedforums.com/cgi-bin/savagewww.rugerforum.com/cgi-bin/cgiwrap/rugerforum/Ultimate.cgi?action=intro
www.unitedforums.com/cgi-bin/remfcgi/Ultimate.cgi
www.perfectunion.com/ubbcgi/Ultimate.cgi
www.parkcitiestactical.com/cgi-bin/Ultimate.cgi
www.unitedforums.com/cgi-bin/mfcgi/Ultimate.cgi
www.mark23.com/mark23-cgi/forum/simpleforum
kalashnikov.guns.ru/wwwboard/wwwboard.html
ubb.hkpro.com/cgi-bin/Ultimate.cgi
www.hk-forum.com/cgi-bin/cgiwrap/hk-forum//Ultimate.cgi?action=intro
glocktalk.com/
www.unitedforums.com/cgi-bin/glockcgi/Ultimate.cgi
www.gunweb.com/forums/index.html
216.88.255.50/cgi-bin/Ultimate.cgi
www.gunsnet.net/webboard/wbpx.dll/~gunsnet
www.webrounded.com/cgi-bin/ikonboard/ikonboard.cgi
www.gunhoo.com/ubbcgi/Ultimate.cgi
www.gunandknife.com/boards/
www.graybeardoutdoors.com/forums/
www.varminthunters.com/forums/ggvg/index.html
www.thefiringline.com/cgibin/Ultimate.cgi
www.fnfal.com/falfiles/wwwboard/
www.entreprise.com/cgi-bin/ubbcgi/Ultimate.cgi
www.egroups.com/community/
www.unitedforums.com/cgi-bin/czfcgi/Ultimate.cgi
www.unitedforums.com/cgi-bin/cfcgi/Ultimate.cgi
www.unitedforums.com/cgi-bin/brownfcgi/Ultimate.cgi
www.unitedforums.com/cgi-bin/brencgi/Ultimate.cgi
www.beretta-forum.com/cgi-bin/bfcgi/Ultimate.cgi
assaultweb.net/cgi-bin/Ultimate.cgi
www.thearmedcitizen.net/cgi-bin/ubbcgi/Ultimate.cgi
www.armalite.com/newphorum/index.php3
www.unitedforums.com/cgi-bin/ar15cgi/Ultimate.cgi
www.ar15forums.com/cgi-bin/Ultimate.www.unitedforums.com/cgi-bin/ak47cgi/Ultimate.cgi
kalashnikov.guns.ru/wwwboard/board4/
www.ak-47.net/akboard/Ultimate.cgi
www.ak47forums.com/cgi-bin/Ultimate.cgi
www.50world.com/forums/
www.22world.com/cgi-bin/Ultimate.cgi
network54.com/Hide/Forum/goto?forumid=14837
www.gunandknife.com/boards/
www.weaponforums.com/Ultimate.cgi?action=intro
www.subguns.com./
www.scfirearms.org/cgi-bin/Ultimate.cgi?action=intro
www.ak-47.net/akboard/ultimatebb.cgi
www.hs2000talk.com/
www.beretta-forum.com
www.shooterstalk.com
www.m1911.org
www.thefiringline.com
www.thearme