MM Brass or MM Brass Metalizer? I use their metalizer and it adheres exceptionally well. Make sure it's very well stirred/shaken. Then take paint from the upper sides of the bottle, there's more pigment there.
Whenever possible, use the correct color. Brass is close to gold, but next to each other you CAN tell the difference. Gold is "warmer". The slugs should be copper with a gunmetal belt. You can put a drop of black wash to tone this down and add some definition between the bulllets.