Reimer Johannsen: http://www.reimer-johannsen.de/

I've ordered RWS brass from them in the past when RWS brass dried up here stateside.

Huntingtons sell PPU brass: https://www.huntingtons.com/store/product.php?productid=17188&page=1

Grafs seems to have the PPU brass mislisted as Remington: https://www.grafs.com/retail/catalog/product/productId/12660

I have used PPU brass in many different cartridges and have always been impressed.

I have used Norma, RWS, PPU, and of course, reformed .35 Whelen brass in mine.