What's everyones favorite bit and mouthpiece for a horse that tends to lean on the bit in a run? This horse has a stiffer and somewhat rollback style on the pattern (he's by BJO), when you pick up on the rein he leans and takes control which is resulting in a lot of hit barrels. Currently running him in a medium shank Elliott Spur Up 03 twisted wire with roller, and beaded curb. He is extremly soft, light and responsive everywhere/anytime except in a run. Just looking for something that will get his attention, not lean and take control, and be able to drive him further/straighter into the turn when needed.

In my experience, it's not a bit thing. It's a seat thing. Keep contact. Use your seat to drive straight past the barrel. Get the hip past the barrel. When you drop outside rein he'll turn. 

Ditto.... You tube has alot of videos you can search on!

Do you have videos of your runs? Watch closely. "Picking up" on the bit does not cause your horse to hit barrels unless..... you are trying to lift your inside hand up, and over the plane of the mane, while leaning to the inside, letting your heel come up, and looking at the barrel. Yes, that will cause you to hit it.

But you see that the bit in your horse's mouth won't matter. You can switch the bits but if you don't switch how you are riding, you will continue to hit barrels.

So be really honest with yourself, and watch your videos, and see what you are doing to cause it. Then fix it.

I would start in your roundpen with a loomis tied around. Then head to someting with a port, broken on the sides. Get some control back - when you pick up your horse should not lean back. Back to horsemanship even if it means going slow!

I agree with Can Can and cindyt.  I basically use the same head gear on everything I ride and have for almost 25 years.  Occasionally I may have to make a bit change but not often.

Yes! training and body position etc all are paramount but my mare was just  like you described.  Through lots of trial and error .. I found the Kerry Kelly Mercedes ported chain was what she responded to best. I didn't want anything harsh or that I had to use heavy hands with  but she is a SOF and was run hard before I purchased her. She handles like dream in  in slow work in a halter, has a great fun disposition and is not a cheater but I simply had to find something that she responded to without heavy hands.