A well choke, and an actuation mechanism for the well choke are described. The actuation mechanism includes a linearly translating drive mechanism which is coupled to a valve member drive assembly through a fluid coupling which facilitates a change in the overall length of the actuation mechanism. Fluid in the fluid coupling can be released in response to fluid pressure exerted on the valve member when it is proximate a valve seat of the choke, to achieve this change in length. In some embodiments, the fluid coupling will provide a retained fluid column and the valve member drive assembly will include a piston with in the fluid coupling which is movable from a fully extended to a compressed, by the release of fluid from the coupling in response to pressure in the chamber reaching a threshold level.