After experimenting with DGW BU0901, 3- groove minies, the Lyman 575213-OS, 3-groove minies, and the Lyman 577611 2-groove minies, I don't use anything but the .58 cal. Metford-Pritchett style .575" diameter swaged minies without any grease grooves. I like the swaged minie for it's accuracy, it's easy and fast loading using marginal lubrication with liquid Lee Alox AND I can effectively use it with a lighter load of 45 to 50 gr. 3F black powder. If I want to raise the powder load to 60 or 65 gr. of 3F, the heavier powder load will not blow the skirt off the Pritchett style swaged minie because there are no grease grooves to give the skirt a place to fail.