Currently I use a single jointed full cheek snaffle with loops. I use that bit because the full cheek combined with the single joint lessens the chance of confusion with rein aids for my green horse compared to say, a French link loose ring. Plus, the bit loops keep the mouthpiece very stable. Is my logic flawed? Do my reasons for using that bit make sense? Can't speak to English riding
. For western...rein aids don't become confused by changing to a double jointed mouthpiece versus single, or an O-ring versus a full-cheek. Some horses like a very stable bit. Others don't seem to care in the least. The rein aids don't create a dramatically different feel for a horse based on mouthpiece or D-ring versus O-ring. Is it considered less than ideal to ride without rein contact with a loose ring snaffle? Would the rings on the bit clank around and create unnecessary "noise" when not ridden on contact, kind of like what would happen if you use metal snaps on your reins?
In my experience, this is a non-issue. I've used O-rings, D-rings and Eggbutt snaffles and never seen a sign my horses is getting "noise" from the bit. 95% of my riding has been with metal clips to either curb bits or an O-ring snaffle. I don't use a draped rein so I don't know what would happen then. But ridden with some slack? It isn't an issue. The weight of the rein is enough to keep things from clanking loosely.
For reference, this is as slack as I ever get:
In an arena or if my horse is worrying, more like this (and yes, Bandit eats in his bit all the time, sometimes with a piece of grass hanging out the side for 10 minutes). The bit is an O-ring single joint snaffle:
Remember, there is ALWAYS weight on the bit caused by the weight of the rein. The bit itself always has weight because it is metal. Also, it is common with western horses for them to carry their bit - adjust it to where they like it in their mouth and keep it there with their tongue. What is the action of a single and double jointed curb bit? I've heard that you should never ever have a jointed curb bit because of the crushing action on the lower jaw...
I think you are referring to the nutcracker action. People think "nutcracker" means the joint pokes up into the roof of the horse's mouth, but nutcrackers CRUSH. They do not poke.
Curb bit or snaffle, it is possible to trap the horse's cheek between the bit and their molars, crushing the skin and either bruising it or even cutting it against the points of the teeth. I haven't experienced it, but Tom Roberts said it happened too often with polo ponies he rode in India - and was more common with snaffles than with curb bits.
IMHO, if you are doing that, you are using too much pressure on the reins and bit. If you ride with some slack, and sometimes have the slack gone as you give a cue, I don't think it happens.
FWIW, I like Billy Allen bits without a joint, but I've used Tom Thumb bits and various single and double jointed snaffles and curbs. If you don't abuse the bit, the bit won't abuse the horse. It really does come down to rider error.
Could you efficiently direct/plow rein with a curb bit that has a solid, unjointed mouthpiece, and not confuse the horse? Would the individual rein action be distinct enough on their mouth if you did choose to direct rein?
Absolutely. Do it all the time in a Billy Allen. In fact, I've often done it with a completely solid curb bit like this one:
Horses do not analyze bits. They don't break things down into components and then try to reconcile the individual actions. They simply memorize the total feel that gives them relief, and eventually that gives them harmony with the rider. Lots of stuff written says you cannot direct rein a horse in the above bit, but I've done it many times.
Also...have a friend in his 80s. He sold his last horse a few years back, but he started and sold horses for 50 years. The solid curb bit above is what he used to START his horses. He wanted trail horses, sold them as trail horses, and said after the first couple of years he threw away his snaffles and just started all of them on the solid curb - without issues.
Again, I prefer a Billy Allen or a curb bit with sides that swivel. But horses adapt quickly provided one doesn't abuse their mouth by snatching on the reins or heaving on the reins like you're hauling an anchor up!
The Billy Allen bit Bandit & I have been using most of this year is hanging from the saddle. I think it is a very nice design. Sweet iron with a copper roller. Sides move independently:
Better view here - Bob Avila bit:
"Does sweet iron vs copper vs stainless really make a difference for the average rider? What about mouthpiece curvature?
Mouthpiece curvature does. Depends on the horse. Some like it. Some dislike it. And some don't care. I think my horses prefer sweet iron or copper, but the evidence is weak. They also do OK in stainless steel.
I don't have any relevant experience on your other questions.
PS: If you want to ride in shows and emphasize the most subtle cues possible....I don't know. Never do that. When I want the horse to do something, I ask him with a "cue". Once done, I stop asking. The times I pull hardest on the reins? When I need Bandit to stop grazing, bring his head up and get moving again. About 90% of my riding is with one hand. Just want you to know where I'm coming from. Different people have different goals and might get different results. Pretty common poses for Bandit & I:
Knowing where people are coming from helps a lot in deciding how much value to give their advice.