You can use the barrel mops for a lot of things. One example, if you have the right tap, drill and tap a 3" long 1/4" steel rod, and you have buffing wheel for inside of your acrylic barrels. Make 3 of them, one for tripoli, one for white diamond and another for plastic polish. I believe mine are the 12ga mops.
If you can find some that are made from cotton, that do not have 10 pounds of lint on them you can use them like a paint brush to finish the inside of wood calls. Unfortunately I have not been able to find any of them in years. There are others, just have to use your imagination.
Marvin