I don't know what part of it is the economy, politics, the RKBA wins in legislatures and courts over the past 15 years or so since the '94 AWB, or the "re-mainstreaming" of the gun culture that's caused it...
But my local gun-club has gone from 120 members to over 250 in the past three years and we're getting close to the point where membership is going to be limited to a fixed number soon, and new members only allowed in as old ones die or quit for the first time in the club's 60 year history.
And club events which are open to the public non-members etc. IDPA, USPSA, GSSF, Bowling Pin shoots... revenue is up at all of them. And other than a board member who's also a gun-store owner pimping the club at every opportunity, we haven't really been advertising or networking any harder.
While I think there's SOME small shred of truth to what the anti's claim, that all the record gun sales are just existing gun nuts buying MORE, there's also a LOT of new gun owners, or low/inactive gun owners who owned maybe one Fudd firearm for hunting, or inherited it, and are getting into new and more kinds of shooting, like EBR's and self defense/CCW.