I played with some last winter, rolling my own for woods cruising before the weather got cold enough that the snakes began hibernation. At a range of about 5 feet, they'd be devastating to Mr. No Shoulders.
That's 7.5 shot on the left, #11 shot on the right. Each loaded in .44 magnum, using homemade wads and Unique powder. They're easy to home-roll, or you can buy the capsules from a vendor.
There's a how-to primer here. LINKY!