Either pull out the rubber bumper at the end of your cue, unscrew the rubber bumper (as in a Joss) or see if it's secured down with a screw of some kind and unscrew it and then pull out the rubber bumper. You'll then either see nothing, a hole to the bowels of your cue, or another big screw of some sort.
That's the weight bolt. Depending on how heavy it is, that's what determines the weight of your cue if you have a bolt. You can replace it with a heavier one, a lighter one, or leave it out based on your desired weight.
Will it screw up your cue? It'll change the weight and balance. It Could be for the better or could be for the worse. Depends on you.
