looks like a food mill or ricer. the circle part would squish the cooked food through mesh ( rusted away) into a pot. that's my opinion.
My Mom had one of those tools, I think she used it to crush cooked vegetables. I don't think it had anything to do with packing fruit jars. I always helped my Mom can and preserve all kinds of food and making cottage cheese, butter, and cooking. With five mouths to feed it took several hundred jars and jelly jars. I still have many of them in the cellar up north. I don't think any of them have much value. We gave about four dozen of them to Mapple Syrup making neighbors to deliver and sell their production. RED Matthews