Would they tell you the specification on the bolt? Or maybe you know. Length and thread is all you would need to go t oa local hardware store right? Maybe I'm missing something. I don't have one of those guns so may be mis-speaking.
I assume he is talking about the breech bolt. You know, the part that holds the cartridge in the barrel and contains the firing pin?
The breech bolt has to be gunsmith fitted to assure correct headspace. If Ruger did have one they would have to fit it.
I sure hope you find it in your stuff somewhere friend. That is a major bummer!
You might also search on Facebook for Canadian gun parts pages - assuming that you do FB. I belong to a couple of stateside ones, and you can occasionally find some uncommon parts there.
This has been a nagging worry for me. What would I do? Probably search every pawn shop looking for a similar long action M77 .470 bolt face rifle and having that I could part it out. After finding the bolt the headspace of the rifle would need to be checked out. You would have a bunch of extra parts after this.
Be sure your bolt stop works well.
Ive seen bolts listed on ebay or other online sales places when I googled them in the past. Seems like they were in the $100-$125 price range. Being in Canada may be a problem. There may be a way to work with the export regs though.