That water quench will add 5+ BHN. If you need more speed then the water quench is the way to go but at 1,500 fps you don't need it. I would just let them cool on an old towel. Age for a couple of weeks and shoot some. Liquid Alox diluted 50/50 with mineral spirits (I use about a teaspoon for 100 bullets warmed with a hair dryer). Two coats should be enough. I would melt the WW's separately, flux a couple of times and skim any non metallic crud off the top. If it looks like a metal scum, stir it back in and add more flux (wax, sap, sawdust etc.). When "clean" pour into moulds. I have a cast iron muffin maker from a garage sale. Makes 2# ingots. These I use in my electric pot. Your mileage may vary. If a wheel weight does not melt, it is probably Zinc. Skim it out and toss it!
Dave