"My horse is currently ridden in a wilkie/gag/pelham and goes along in a nice frame. When I put him back in a snaffle for dressage he goes with his head up and nose out. What dressage legal bits give poll pressure like my wilkie/gag/pelham?"
Bits that use forms of leverage are not dressage legal, only 'direct action' snaffles.
In a nutshell, your horse isn't accepting the bit or working over his back and through correctly. He is setting his neck and bracing against the leverage pressure of the bit which encourage the head to drop and nose to come in. This is what we refer to as a false frame. The head and neck are in position and the body is essentially just dragging along behind.
What we really like to see is a lifted back, the horse engaging his abdominals, stepping under nicely with the hindquarter while reaching forward into the bridle and taking a good steady contact. This is when you are truly working your horse "on the bit". Easier said than done I know! Its all a work in progress and will come down to a lot of training hours and work strengthening the right muscles.
We can often assist in achieving and encouraging this 'stretch' into the bridle with the right bit.
A lot of the time to get the horse reaching for the contact we need to develop this horses confidence back in the bit.
For those in a Wilkie - The Neue Schule Turtle Tactio which is very very kind on the tongue and bars, great for a really sensitive horse, takes up minimal room in the mouth due to its cleverly flattened design and encourages the horse to take the contact with a relaxed jaw and neck.
For those in a Gag - The Bombers Lock-Up Baucher has been a wonderful transition bit. It provides a gentle mouth pressure, not too much on the tongue with no nutcracker action due to the locking mouthpiece.
For those in a Pelham - The Trust Ported Eggbutt has been a god-send for these horses as it uses a tongue relief style mouthpiece with a forward curve to encourage contact seeking. Its a fixed side so it sits very still and consistent in the mouth. Being non metal it really encourages the horse to salivate and relax the jaw.
As always, we are available for personalised bitting advice on (08) 8388 8472 or email firstname.lastname@example.org