wheel weights are plenty hard as is for range shooting (generally 9-10 BNH) but if you water drop them they'll be even harder.
powder coating is the best way to go nowadays.
if you're still learning about it I suggest you read through this thread.
http://singleactions.proboards.com/t...ating-question
Dick Thompson aka Sixshot is a Major Handgun hunter and when it comes to cast bullets I trust his word over just about anyone else's.