You need to use a lower bounce wedge and use more of the leading edge than the bounce so the club digs a bit more before it comes out so you don't thin it
As well as using a lower bounce or square face, you may change your angle of attack. Firmer sand lends itself to a more "V" shaped swing, earlier wrist cock back, steeper angle down, and a recock through to finish. I love firm sand. Be aggressive!
on really hard bottom I go with my lob wedge, square face, and hit closer behind the ball giving the club less chance to bounce before contact. depending on the conditions I may open it up and play it like a normal bunker shot still with lob wedge.
I am not sure but a low bounce lob wedge may still have more bounce then a regular baounce gap wedge.