The older Manfroto Pistol Grips were noted for having a lot of play, particularly the vertical ones. I had two of them, both with the same problem. The horizontal grips did it as well, I had one.
I have mine bolted to a light table and find it handy for product shots. Worthless for a tripod or big lens.
Finally, I spent the extra $$ on the new model, it does not have play, but it takes a tight squeeze to release it, and since I have carpal tunnel, its not the easiest thing for me to do.
If you buy one, buy one that can be returned if you do not like it.