As a traditional muzzle loader shooter of patched round balls, I have had occasions, and guns, that I use felt wads over the powder on. I have found that if the area in front of the breech plug is eroded due to improper cleaning, the use of a felt wad will help maintain accuracy, and sometimes improve accuracy by providing a better gas seal. I also use an unlubed felt wad (of proper caliber) over the powder on my hunting loads where it is possible that the load may be in the gun for a week or more before the gun is fired or unloaded at the end of the season. The wad in this case protects the powder charge from lube bleeding from the patch.