4 g2, You really need to read up on bullet casting. A Lube and Sizer uses stick lubes. The simple Lee sizer requires an Alox tumble lube before sizing.
If your blocks throw a bullet the correct size you can tumble lube. If not you will need a sizing die. The hard high antimone lead will run larger diameters and lower weights. The softer or lower BHN bullets will run smaller diameters and higher weights.
BHN is used to test the hardness of metals in this case lead. Pure lead can run a BHN of 5 to 6, Linotype or Monotype may run a BHN of 20+. Foundry lead a BHN of 27.
The reason we use the BHN is to match pressures to alloys. I would use Wheel Weights [WW] as shot is very expensive. You need to understanding "Fluxing". I might add in order to use chilled shot you will need to add tin. Without tin it will not pour or fill the molds correctly.
Tumble lubing is easy. A bullet of correct diameter can be placed in a samll plastic pale. A few squirts of Lee Alox shake the pail around until the bullets are coated. Let them set over nite and load. For a nice finish shake a small amount of Motor Mica on them.