Best results will come with a cylinder full of 3F - with room, slightly compressed for a thin lubed felt wad, then oversize ball.
Measure and make sure the cylinders are larger than the groove to groove diameter, the get a mould corresponding to that diameter.
Some guys pour the powder, seat a ball THEN fill the chamber mouths with some form of grease - Crisco Shortening is often used.
This will work, but is really messy and runs with a hot cylinder. Normal BP bullet lube is better, as-in a concoction of beeswax/Vaseline. More beeswax makes it stiffer, but 60:40 works well. By Volume.
Lyman's BP BP Gold or SPG can also be used - made a bit softer with added Vaseline or some oil, like Olive, Grapeseed or Avocado oil.
Better accuracy will usually appear without smearing grease over the ball, and using a felt wad, as taught by Elmer Keith.