1100 to 1200 grains 4F with 3 balls atop and gun set off. Stock breaks, bulge in barrel and tip of muzzle banana out. Don't try this at home. What a public service.
https://www.youtube.com/watch?v=2StO9a1CYbk
https://www.youtube.com/watch?v=2StO9a1CYbk