If you can place that ball in the vitals it will sure do the job. Do some range work and at whatever range you can keep 5 of 5 on a paper plate, that will be your maximum range. There are a lot of different ways to load a smoothbore, with or without a wad, with or without a patch, different ball sizes, 60 to 120 grains of powder, various lubricants, etc. Getting the most out of your musket takes a lot of shooting and experimenting but the most important final result is to know, absolutely know your musket and it's limitations.
http://www.muzzleloadingforum.com/fusionbb/showforum.php?fid/16The link is to a site where you can learn all you might ever want to know about muzzleloading smoothbores. Don't just assume that because it's a smoothbore accuracy has to be lousy. Many smoothbores will punch fist size groups at 50 yards and a few will do nearly as well at 75 yards, but not with just any load you happen to try, smoothies are picky as to what they want to shoot.