Slop in the hitch

I have the Reese with a slider and have noticed the same thing. I did not notice any banging before I added the slider option. In other words, the initial Reese jaws and mechanism was quiet. After buying a new 5th wheel I decided to also purchase the slider bracket rails just in case. So far I have never had to use it. Wish I had not spent the money to convert my hitch to a slider because this is when I noticed the banging when stopping or starting. However I have solved this problem by experimenting with different thickness shims I have made from sheet metal. I put them on the 4 legs of the hitch and make them as thick as possible to still enable the 4 pins to go in tightly. Experiment with different thickness shims to find what one you need then make some spares to carry. They will eventually wear out and become thin which will make the banging return.