Any firearm (not full auto) is automatically C&R if over 50 years old, which makes my October '65 Win 95 eligible. The earlier AR15's have been eligible for a few years already. Even AK's if semi auto are, along with FNFAL's, HK91's, etc etc.
It's about being 50 years old.
What some face with buying them to ship to their home are FFL's who aren't well versed in it and who refuse to cooperate. To quote the ATF, "it is not necessary for such firearms to be listed in the ATF's C&R list."
https://www.atf.gov/firearms/curios-relics
It's about being 50 years old. No modifications or caliber changes seem to be allowed, which puts some of those old WWII era Mausers rebarreled in .308 into question. Do gunmaker enhanced early M39s like Devel put out qualify?
Note that some firearms on the list are considered curios already, even tho not 50 years old. FN HiPowers "Rennaissance" 9mm, up to 1976 are C&R. The newest would only be 41 years old. Most of these are $2000 and up heavily engraved and some gold plated. Not your average Alaskan guide bear gun.
As the link to the Forgotten Weapons site notes, there are over 10,000 SP1's - semiautomatic AR15's eligible. In the language of the anti gunners they would state that we could buy an assault rifle "thru the mail" and ship it directly to our home without any FFL or background check. Technically accurate enough for them. We are left to argue what constitutes an assault rifle. I don't think being C&R would change CA or NY's laws. I guess that leaves more for us.
We are now looking at any semi auto gun made before 1967 or so being C&R. Next year it's 1968. The year after, 1969. Keep going far enough and the HK91 I bought in 1978 will be C&R. You younger guys have some good times coming.