I use http://www.friendswoodbullet.com/. Several thousand rounds without a single hitch - Richard makes some high quality cast projectiles and generally has them at better prices than any of the dozen or more companies I price check whenever I buy.
He's a small, one man outfit and all he does is cast projectiles out of his garage. He has a sweet setup that would make most of us drool.
That's who I use too. Very satisfied with the quality. I've shot thousands of his and never a problem.