I don't know about the Lee, but I have the Lyman 1 1/8 mold and at 50 yards from a 20" smooth bore slug barrel from my 870 I group into about a 3" diameter grouping with a 3x scope on the shotgun. You will have to find the right powder amount for your load. Turns out 24.5 to 25.5 grains of Herco is what does the trick for my load.