Well the problem is most any black powder smoothbore will cost some serious money. Even the inline rifles will push the $300.00 limit. Cabela's sells double for over $600 and you can get some old style barrels that will fit other rifles but again, you are going to spend some serious money. Perhaps look for a large bore musket. You can shoot shot out of them if you want. Be advised some of the older muskets that did shoot shot, do not have a lot of range. If you want black powder with range, you want to look at the Knight TK2000 or the White Tomanator.