I have a 410 bolt action shotgun my dad gave me when I was 14. We spent hours sanding, polishing and dad cold blued it (even though he used heated bluing liquid)....36 years down the road and the barrel is looking like its rustic under the surface....

I have seen that some people recommend to conserve old guns, that you need to boil the metal parts in water..apparently there is some kind of sorcery that will turn any rust into a black oxide that can be then carded and then polished or oiled to stop the rusting....

Is this something that any if you (my imaginary friends) have heard of...or should I get someone to hot blue the barrel?

Or should I parkerize it and be done with the fancy finish and not worry, as parkerizing last a long time and is a great finish to prevent damage?

You might be able to convert the rust as you've read

https://www.youtube.com/watch?v=62_pKoYje9o

https://www.youtube.com/watch?v=TaYluvfRZeA

Just a thought but maybe look at some of the work Coyotekiller does on weapon finishes. He did a revolver for me and it's fantastic. He advertises in the classifieds.

So it's a bolt action shotgun. Most of them are worth $50 or so.
But the one you have has sentimental value because you worked on it
with your Dad! As long as you understand that any money you spend on rehabilitation is likely wasted from an investment perspective, think about doing refinish work that makes you happy. The sky is the limit...
24k Gold Plating.
Hard chrome.
Brushed electroless nickel.
Re blue.
Parkerize.
Various spray & bake finishes.
If you decide to parkerize, send me an email. I know a guy.
I'm waiting on a revolver cylinder to arrive from him.
I also got a family/sentimental bolt action .410 shotgun fixed up for a family member.
We spent more on ancient new/old stock parts than what the gun is worth.
But seeing the smile on the owners face made it worthwhile!
Make sure you post a photo when the project is completed.

I have ‘rust remover’ on the shelf & some home bluing bottles, mostly from Brownells. I have sent a barrel off for ‘real bluing’(relative’s Fire).

With low cost/value guns I just try touch up myself.

I've done a bit of Rust Bluing and it's an easy process to do. Start by cleaning whatever you are bluing with steel wool or a brush. Then wipe it down completely with acetone. Soak whatever you want to blue in this acid solution and let it bubble for 10 minutes or so. Add a bit of salt to white vinegar and the result is a solution of vinegar and hydrochloric acid, an excellent solution for starting the rusting process. Then hang the item in a rusting box (home constructed, could use PVC Piping) that is fed a steam solution generated by salted boiling water. One you have a nice even layer of red rust you then need to place your item in a tank ov boiling water for 10-15 minutes or however it takes to turin the rust completely black. Carding is a bit tricky because starting out everyone wants to card the surface hard and deep. DO NOT DO THAT, you will only scrub off the layer of black oxide you have just applied. When you card the surface all you want to do is knock off the loose whiskers of black oxide and nothing more. The Last step is to repeat this entire process. Note, don't go past this repeat line until you have done a minimum of at least 10 cycles BTW, for a prettier finish you'll at least 15 repeats.

Note, Black Oxide is a Lattice Structure and by repeating this process multiple times (15-25 times or more) you are making that lattice denser one little bit at a time. Also, you will NOT get a high gloss blued finish with rust bluing. Spend enough time repeating the process to build up enough density and you can have a satin finish that is a bit more useful on a working shotgun due to less glare. Finally to make your black oxide truly rust resistant you need to OIL the finish with a water displacing oil. One of these is WD-40. Downside to WD-40 is that regular re-applications are needed to maintain a high level of rust resistance.