Hi;
I believe you're refering to a .32 Blackhawk made specially for Buckeye Sports quite a few years ago. I'm pretty sure that they used a .312" bore size. I have a .32 Mag Ruger, and I too have had pretty good luck with SOME bullets that were .308 diameter, especially Hornady's 100 gr Short Jacket. They theoretically shouldn't group, but do. The short jacket usually separates from the core if used on falling plates and kind of flutters to the ground.
Bob.