The Walkers will do 60 grns as shown here but you need to remember to put up the mono-pod after each shot. It is a lot of fun to shoot though.
My understanding is the dragoons will only do 50 because the cylinder is shorter but I have never shot one so I don't know.
Keep in mind the Walkers are big, darn big.
Here is my Walker next to my 357 Maximum SBH. The SBH is already a huge one for the Rugers with the extra long cylinder. Compare that to the Walker.