Rifled Harlot Barrel

May require some drilling. You'll need 15mm 9/32 brass or aluminum tube with wall diameter of .14 or .28. If you use the .14 the round will be looser but should still work. If you use the .28 wall tube it will have to be drilled out with a #1 drill to fit the round.
I'm not responsible for what you do with this file. Don't hurt yourself be carful.
The brass tube goes on the breach side after it's drilled to size make sure you epoxy it into place. File any bits sticking out and bobs your uncle.
Apparently any home made pew has to be rifled or it's a short barreled shoty. If you don't want to use this barrel liners are available.