Green AQHA mare, ornery with the bit.

I just started working with an out-of-shape 8-year-old AQHA mare who is just lovely. Her ground manners are excellent, doesn't seem to spook at anything, sweet personality, etc. She has been ridden off and on for the past few years, but nothing consistent. So she's green and has never quite been finished. She was originally ridden western, then English, then western again. And I am riding her western since this is definitely what suits her best. I like this mare a lot, but I am having a problem with the bit.

I have tried an eggbutt snaffle (which had previously been used with this horse), a d-ring, a loose-ring, and a full-cheek snaffle, but the mare shakes her head, halts, chomps the bit, swishes her tail, etc. This behavior begins once she has the bit in her mouth, even with no contact on the bit (although contact intensifies the behavior, especially if I am mounted and asking her to walk). I have tried various headstalls for fit reasons and this has not helped.

I have no idea if this behavior is truly due to the bit, or if the mare is just out of practice (only ridden a handful of times in the last year) and just balking a little at the work. It occurred to me that maybe I should go back to square one and try a bosal-type non-mechanical hackamore. I have never used one of these before, so I went to a local tack shop for advice. The woman there told me that nobody should use a bosal if they haven't used one before. This begs the question: how does anybody ever start using one?! Regardless, she told me "no" on the bosal and suggested we have the mare's teeth checked out, which we will do.

I ended up buying a thicker rubbery snaffle today, and I'm going to try that tomorrow. If the behaviors continue with the mare seemingly hating the bit in her mouth, what do you suggest? I've been told that I should remove the reins, put the bridle on the mare, put her in a stall, and let her get used to the bit that way. Is that recommended?

Does anybody have any advice for me? This is a "backyard" mare who is loved, well taken care of, and in good health. The owners simply haven't had time to ride her consistently. The mare is not working with a professional trainer, and it doesn't seem to me that one is necessary (this is not going to be a show horse, just essentially a trail horse). Nevertheless, the woman at the tack shop brought it up immediately, as if to say I shouldn't be riding this horse because I'm not a pro. I've been riding for 35 years, shown western please and hunt seat, owned three of my own horses over the years. I'm not an expert and I'm not a trainer, but I believe I have enough experience to slowly bring a green horse along. Or do I?

No. This will not get any results you want. If the problem is pain (which you should check out first) then this is only going to hurt her. It may be somewhat effective if she simply doesn't like the bit, but I doubt that's the case. Besides, why would you want to basically force her to accept it? Some horses simply can't stand bits and almost have to go bitless. There's nothing wrong with that.

Please read the thread 'Will your horse respond to the bit?" sticky on this forum.

This is not an uncommon problem when you ride a horse with little training info, and if her teeth check out ok, you will have to keep looking for a bit that she likes. Can you contact the original owner to find out what they used on her? If you can please do, as it could save you much time and money.
Your description of her reaction to the bits you have used make me think she has a problem with her teeth, so have her checked before you waste time changing bits around, and then when she is sound of mouth, take your time and use the bit for a few rides to see if she settles in, as after having several bits in her mouth that may have been causing pain it could take a time or two for her to figure out the bit is not going to hurt her mouth,
Our mare was ridden in a low port curb bit (previous owner not original owner) but they had problems with her head shaking etc. so when we got her we put her in a soft split bit (sweet iron snaffle) after trying several low port curbs and she became a different horse. No chomping, no more head shaking and no more pulling.
Every horse is different depending on how they were started so it will take time and patience to figure out. Best of luck.

Thanks for the help. The original owner used an eggbutt snaffle, but this mare was broke/trained years ago and then ridden very little after. So what once apparently worked isn't working now. I'll go ahead and have her teeth checked and keep you posted.