While there are some torturous options in the bitless world like this
The general rule of thumb is that tack is only as harsh as the hands on the reins. IME, anyone who says "This piece of tack is cruel" simply doesn't know how to use it properly.
If you don't have good hands, you can skin a horse's nose and jaw up with a bosal, you can bruise/bloody their mouth with a snaffle. Anything
can be used to cause pain if it's used incorrectly.
However, used correctly
, a snaffle is no harsher than a halter and that's no harsher than a double bridle or spade bit. After all, a good horse shouldn't wait to respond to pressure
, they should respond to the movement
of the tack. IMHO, that's why good western horses are ridden on loose reins. You don't have to pull on them to get a response, you simply have to pick up enough slack in the reins for them to feel the bit shift
in their mouth.
You can use a bosal, but unless you are under instruction from someone experienced in using them properly, you likely won't achieve the level of responsiveness seen in good young bridle horses. There is a proper way to use them to achieve and maintain a soft and supple horse. As EquineObsessed said, there are trade secrets to fitting them and using them correctly. If it's not fitted or used correctly, then it's no different than riding in a very stiff, and very expensive
, rope halter.