I have only been casting for a year or so and have 3 molds. I have never tried any type of lube, started with PC and see no reason to do anything else, so on the 2 molds I ordered from Accurate, I opted for no lube grooves. My thoughts are that my non grooved 9mm boolit is less likely to be swaged when crimping, which I was having trouble with when loading my Lee 110gr SWCs. I知 wondering if there are any advantages or disadvantages to grooved vs smooth boolits that I知 not aware of.