These question's are always easy for me. I don't invest in rifles! I have one rifle, custom 1903 by Paul Jaeger they was appraised in 1993 at $7500! The stock was worn and needed refinish and the barrel was in bad shape due to primers. it's my elk rifle now. But how many 1903's attain that kind of value, it's been sporterized! Pre 64 Mod 70's command a good price but it is my opinion that they are no better than new mod 70's! That's not to say that people are wrong for spending that much on a used rifle if it's worth it to them.
Your little 22 in 40 years will be what ever you can get for it, no more and no less. Shoot might be worth almost as much as it cost new! I don't know a lot about investing but let's say it doubled it's new price in that 40 yrs, I think a good stock would be worth far more.
I didn't use my 1903 much because first it came from a very close friend and second because it was worth so much. Well a couple years ago it became a cast bullet rifle and last year it became my elk rifle. I've refinished the stock so the value probably goes down but what do I care? I use the rifle. If it had been offered ne to buy, no way would I spend that much on a rifle but someone would have. Just have to wait to find that person. Use your rifle. Could be it will make memory's far more important than it's collector value!