Hey Hal, you remember that guy on OG long ago that made up a Hevishot recipe and shared it with a bunch of folks? Somebody finally tested it and it was over 17,000 PSI.

But as far as I know, it didn't damage any of the guns. It takes a lot to blow up a shotgun unless you have a barrel obstruction, but why take the chance? You need to do everything just right to hunt turkeys with a .410, and even then you might not get a very effective pattern. Buy some shot from Hal and get a proven recipe, and then test the pattern. Good luck with it!