Bitless or stronger bit?

[iloveCharlie5]

Hi!
My mare is 16 now and i've had her for a year, in this time shes always been very heavy on my hands, she leans on the bit and for some time she was in a double bridle. However, recently she has taken to bolting, and even though the lady who rides her for me when i have school had her in a swales, she still went ballistic and bolted with her. She isnt scared or in pain, and i'm at my wits ends because i'd love to be able to ride her in a very mild snaffle bit and for her to be light and responsive-when i think we're getting somewhere she bolts and i have to go back to a strong bit. I've heard a lot about bitless bridles such as the Dr. Cooks, would this be something i could try? She works very well on the ground in her rope halter, and since she has such a hard mouth I wondered whether taking a bit out completely could be the answer?
Thanks!

[Kaliska]

Dr Cooks allow you to trial their bridles before you buy, but it sounds like you need some help with the fact that your horse bolts, rather than just thinking about the Bit. Liz Pitman, one of the experts on here is usually really helpful!