I’m almost afraid to ask.....which Alpha nose cone? There have been at least three different ones (four if you count the few years when the Alpha might have come with an Alpha III nose cone). There was the original BNC-50K balsa one, a blow-molded plastic nose cone that’s pretty close to the same shape, and the narrower blow-molded plastic one that has been used since the early 1990s.
The current one is in the PNC-50 assortment Estes sells. I probably have a spare or two but I’m not at home right now so can’t check. I’ll be back Friday.
Of the two “BNC-50Ks” that I know of that are available, the one at eRockets/Semroc is closer to the original shape than the one sold by Balsa Machining.