APP is now producing powder again after their plant explosion.
The powder with the original APP label is available for purchase from the following; outfits: bulletsbyscarett.com, lg-outdoors.com and wholesalehunter.com.

It's also being sold under the Shooters World label @ grafs.com as Shooters World Multi-Purpose Black
(This Black Powder substitute is made in America for Shooters World by American Pioneer Powder).

https://www.grafs.com/retail/catalog/product/productId/83678

https://bulletsbyscarlett.com/shop/ols/products/app-american-pioneer-powder-black-powder-substitute

https://www.lg-outdoors.com/Search/Keyword?keywords=american%20pioneer%20powder

https://www.wholesalehunter.com/Search/Keyword?keywords=american%20pioneer