Always worth an updated re share as still a problem unfortunately :

A frequent query on the advice line is "i need a bit that is going to stop my horse:.....leaning, running out, running off when I want to stop, etc etc - help!!"  " Hes's the same in EVERY BIT and I have tried EVERY BIT ........what shall i do? ? ?.  As usual, there is never just one straightforward reply.  Many factors need to be taken into account to try to rule out the reason for the leaning and one of the most important is ; "does the current bit fit?" 

A lot of the bits I see are at least 1/2" too big and therefore sitting out to one side under rein tension.  This can result in, depending on how the noseband and bridle support the bit, the bit hanging out to the left rein even when you are on the right rein.  Sometimes it can even slide across the tongue quite harshly when a change of rein occurs and riders wonder why their horse throws its head.  I won't move on to recommend anything until I have worked through my process which includes this important factor and some customers can get quite frustrated "just recommend something!".  Erm, no; I do this job for many reasons, including that I am actually quite good at it so just have a little patience and send me the information I need. :-) 

The bit needs to sit centrally and needs assessing with and without rein tension as to whether it fits or not.  If you are not sure, feel free to send photos to me at gail@horsebithire.com and I will check it for you :-)  This will happen before I recommend anything.