The question is why should contact increase beyond a light connection/a taut filled out rein? What are you asking of the horse (laterally/longitudinally)? It might be more the posture and bearing of the horse than the bit type per se. For a horse that crosses the jaw, a drop noseband can prevent this. Perhaps you need to go back to work in hand to help to educate the mouth progressively. You do want the horse to softly chew and swallow, just not to jammer/etc. A horse that roots is usually against the hand/out of balance/too much on the forehand, so half halts have to be correctly applied. Has this only recently stated with lateral work/2nd level, or before?
I agree with the horse being uncomfortable somehow, whether it be the bit or your hands or both. Obviously we don't know your riding so a definite answer can't be determined.
To answer your question about tight nosebands, I hate them and find them useless. As someone else mentions, I believe they cover up a problem but don't fix anything. I know cranks are comfortable because they are padded, and for aesthetics I don't mind them, but I would never "crank" them tight. I'd still want at least 1 finger under it. I don't mind flashes as long as they're not too tight, some horses go well with just a touch of pressure there.
The owner of the last barn I was at used to put pads under the crank nosebands in order to crank them even tighter. I found this extremely unnecessary. I can see if a horse has a really small nose and you can't punch holes in a certain noseband, or for more cushion without being tighter, but she did it simply for more leverage. In this particular case, I did NOT like her riding, I found her horses to be quite incorrect, her scores reflected that, and somehow it kept going on I didn't want to say anything because it wasn't really my business since all the horses were very healthy and happy otherwise. I just quietly moved rode my way and progressed further than she was at the time
I have gotten into the habit recently of riding in our arena with mirrors at least once or twice a week and concentrating on my mare's mouth. She's very fussy with her head and can be busy with her mouth. But she is telling me something about my hands and seat every time. I have been experimenting with the way I ask things of her, and can see that when I have very soft contact, and she is relaxed and understands me and is working with me, her mouth gets very quiet. If I were to try forcing her mouth closed I am certain her mouth would never get quiet, and I would never learn the lessons she has to teach me.
Faulty riding is usually the core issue. I see lots of people who try an endless string of bits to try to "fix" their horse's problems. It's always easier to blame the tack.
I do believe in checking rider issues but since I have one of the problem chewers I understand how frustrating it is and how difficult it is to try to maintain a steady contact when the horse is constantly chewing and rooting. From the first time I bridled this mare, she chewed her bit,I was advised to put the bridle on and pony or lunge her, give her a job, and she would forget about the bit and accept it. NOT!
Whether she was bridled for five minutes of for an hour she never quit chewing.
No mouth problems,everytime I have her teeth floated I have the vet look for anything that might account for her fussiness. I have had visiting clinicians check her bridle, bit fit.....sometimes they would make an adjustment, this guy would tighten, that guy would loosen.... but nothing made a difference.
Just does not like anything in her mouth.
This mare is quirky about a few other things as well.
For sure she has been my greatest training challenge. She has been undersaddle for 2 1/2 years and since I switched to the happy mouth she has improved greatly but still chews.
It may be you, it may be the bit, it may be how the noseband affects the stability of the bit. I tended to think that it was mostly about the rider's hands...until I started my current young mare, who gaped/chewed/resisted a double jointed lozenge bit--with no reins/hands attached to it, and a simple caveson noseband or even no noseband! She has ended up, and is quite happy, in a Happy Mouth mullen mouth, with a Micklem bridle.
I can think of two horses I know with similar issues due to allergies. IMHO, it always pays to eliminate possibilities of physical discomfort.
I also agree an eggbutt would be a smart choice to try, especially if you can borrow one. I know many KK/HS dealers offer a 'rental' trial program which is very helpful and quite cost effective. They have an eggbutt KK Ultra I have nick named 'The Miracle Bit'. Every horse I have put it on has become more willing to take the rein forward and become more responsive to smaller aids.
I'm kicking myself in the pants as I reply because I loathe internet bulletin board screaming fights, however, I feel the need to defend myself to the keyboard-jockey DQs who entirely blame the rider. I have to say, I'm a darn good rider; well educated on and off the horse, life-long rider, long time student of classical dressage, and recipient of top notch training from experts. My horse roots because he is a dominant butt head. He roots standing still, on the longe and under saddle. The rooting has diminished as his respect for people has grown over the years. I'm not that worried about the rooting because he stops it with a light tap of the whip on his neck. The working of the bit is a chronic-intermittent issue, even with my high caliber trainer with the most sympathetic hands who had him in full training for many months in his formative years.
I appreciate the constructive ideas, different bit and tack adjustment ideas. I'm afraid it's a complex problem that is masked by a tight noseband and not easily remedied, that's what I'm taking away from this discussion. Blaming everything on hands or bits sounds nice and classical and easy and probably makes some people feel smart and above the hoi polloi but I'm looking for ideas that I haven't already entertained. Thanks to those who are kindly offering suggestions; I take them to heart. The rest of you can....
quietann, I mean general allergies. Ragweed, pollen, mold, etc. Stretching the neck, even without a sneeze or cough, helps clear whatever gunk might be restricting the airway. I had my retired guy allergy tested last year and was surprised at some of the results. (COTTON?!?!?! Oh, come on!)
Dogsandponies, good luck sussing out the root of the issue. Complex problems are a PITA.
I just thought of another thing, too... I think they're called crescent nosebands. They have a half-moon metal shape that kind of wraps around the bit. I would double check this but I am 90% sure they are legal because a friend researched them a couple of years ago and showed successfully with it. You don't have to make them super tight, but maybe it will help your horse with the problems.
Broken record here. It's all in the seat. No seat, then hands can't work independently from the seat. If the hands cannot work independently from the seat then you will be constantly banging your horse in the mouth. It might even look OK to the average rider, but it isn't ok to the horse. Horse roots to stay away from the pain of a rider that doesn't understand and sympathize with the horse.
You don't have to be a good rider. Ride on a loose rein if you don't want to put the work and understanding into it for the horse's sake.