What are some bit suggestions?

Snaffles are usually pretty good for barrel racing because the broken middle allows you to have more control around the turns than a solid bit would. If you are certain that the bit is the problem and not training, I would recommend a gag bit. I used to ride my barrel horse in a gag bit but ONLY because his old owner rode him in that and he was at a level in his training where a snaffle wasn't appropriate for him anymore. So, I would consult a trainer.