The finest moving target shooter I ever saw used a peep sight! I personally witnessed the demise of two deer running on one occasion (sorry, it wasn't a muzzleloader, it was a Mauser), and a solo buck on another. The animals were all in the 50 yard range, but in all three cases, the back was broken above and just in front of the shoulders. He liked that shot. To practice, we'd go to a quarry and prop 5 gallon paint buckets at the top with sticks and shoot them until they'd roll and then bang away as they rolled down hill. My Dad was amazing!
Peep sights are tops for hunting.
Dan