If you can find an appropriately-sized stainless steel ladle with a lip, grapple it unto your kitchen with hoops of steel. They are perfect for the job, but hard to come by. I know they exist. I'm sure I have seen one. But I have not found one when I have gone looking. Alternatively, there are, I believe, metal funnels designed for the purpose. Metal, natch, because the stuff is usually hot (and because you can sterilise them) and designed for the purpose in that they have a wider bottom opening (so your jam doesn't, well, jam!). Come to think of it, I am sure there are specialist shops that would have these things. The same sort of place where you can buy preserving rings. I may just go and google now!
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