https://www.survivalistboards.com/threads/loading-410-metallics.962928/

This is the best write up I have read on this subject. It took me a couple days to recall where I had seen it. I book marked it for future possible use. Deals with fire forming and some basic loads. Also mentions how to get around the wad not sealing well to prevent powder gas blow by. As always read, think about things and proceed with reasonable caution. Remember what Abe Lincoln said, "if it is on the internet you know you can trust it".