Military users along with American shooters and reloaders. The whole basis of the Hodgdon powder company was buying surplus powders from WWII and selling them to handloaders, and many train carloads were consumed this way. Then, during the Vietnam war Olin Corp found a way to recycle old single-based stick powder into new double-based ball powder to fill the millions of rounds of ammo being expended in SE Asia. I would guess the last of the WWII powders was gone by 1970, and that whoever is perpetuating this story at your gun club is therefore at least 50 years out of touch with reality.