The hop-up is one of the most important systems in an airsoft replica. Its function is to apply a backspin effect to the BB in order to increase its effective range and improve trajectory stability.

One of the most common mistakes when adjusting the hop-up is applying too much pressure. When this happens, the BB tends to rise excessively at the end of its trajectory. The result is usually an irregular flight path that reduces accuracy.

Another frequent problem is adjusting the system using low-quality BBs. Balls with inconsistent tolerances can produce unpredictable trajectories, making it difficult to find a proper adjustment.

The weight of the BBs also directly influences the adjustment. Changing from 0.20 g to 0.28 g without modifying the hop-up can significantly alter the shot trajectory.

In addition, many players forget to regularly clean the inner barrel. The accumulation of dirt or residue can affect the contact between the hop-up rubber and the BB.