I think Nosler sources their brass from any of the makers mentioned. I just got some Nosler 264 WM brass that is headstamped Nosler but is exactly like the Winchester brass, it even weighs exactly the same. Norma 35 Whelen brass is great news and plan on getting them when I can. I had some real bad Remington brass but my new lot is good.
I checked the Nosler Whelen loads and they are headstamped by Remington. I know the 280 Ackley stuff they sent has brass by Norma. I quess they use multiple sources.