I suspect that having a forum "explode with activity.... from young shooters" may not be a priority for the owner of The Firing Line.
People here do post about airguns in the appropriate forums (rifle, handgun, competition, hunting -- depending on the specific topic) -- there are quite a few of us who shoot 'em.
And if you're looking for airgun forums, there are quite a few out there:
AirGunForum
http://www.airgunforum.net/agf/index.php
Graybeard Outdoors - Air Guns
http://www.graybeardoutdoors.com/php...forum.php?f=77
And RimfireCentral has forums for both air rifles and pistols, as well... just keep scrolling down, you'll get to them eventually...
http://www.rimfirecentral.com/forums/