Chucking?

Have the trailer brakes adjusted, with the brake controller, to come on with and slightly more aggressively than the truck brakes. It is the pin pushing forward as you brake that causes the worse chucking.

Basically, keep the pin back against the jaw,instead of slamming forward and you avoid the chuck.

Dampeners, and air pins etc may help and are expensive but do not salve the basic problem which is bad trailer brake adjustment.