The Brownells brand Classic Rust Blue was back-engineered from Pilkington's formula shortly before they "downsized" me. At the time, Pilkington's products were unobtainable, and it didn't look as though the company was going to be able to ship anything.
Polishing is important with any rust blue product. Never go finer than fresh 400 grit wet-or-dry paper. As has been pointed out, 320 grit is better. Keep all your polishing marks going the appropriate direction. Make sure that your carding wheel or brush or steel wool is degreased...you can introduce oil into the system from it, too.