What did you buy? Was it an old original or of modern manufacture...any choke? If it's old verify the gauge as you may think it's a 12 but it's really a 13. Below are some links that might be of interest to you.
Skychief's Shot Load Link
By popular demand for a sticky showing Skychief's method of loading smoothbores to get the most uniform patterns, I'm posting this link to the thread. The actual thread is a sticky in the Muzzleloading Hunting area of the forum. Click on this link and the computer will take you to it...www.muzzleloadingforum.comCircle Fly Wads, LLC
circlefly.com
Thanks for the information. I really appreciate it!