I still can't find where it has one. All I can find is that it was created in 1963. I can easily find parent cartridges for every other round that I look for. For example, 6mm rem was a .257 Roberts which was 7x57, .338 Lapua was a .416 Rigby, etc. All listed and easily found. I still don't think the .284 Win has a parent case. Designed after something, maybe, but a true parent case, I'm going to say no.
D&T, been meaning to ask you this. i see you use winchester actions. is there an advantage over the 700 action? i ask because one of these days (when the house is paid for) i'm going to have you build me a rifle!