Issues with bucking lip length
Some hop-up buckings (e.g. Maple Leaf – see photo) have a longer lip. It is possible then for some combinations of buckings and hop-up chambers to have bucking's lip protrude into the hop-up chamber's BB feeding hole.
This often causes issues with feeding the BBs into the chamber or even issues with choking of the shot. This is because the lip reduces the space used for feeding the BB in front of the air nozzle. Then, the BB cannot get into the correct position in front of the nozzle or the bucking's lip can roll up and obstruct the airflow during shooting. This can often result in damage to the gears or the piston.
Thanks to the spacer sleeve installed on the lip of the bucking, the total length of the bucking in the chamber is shortened, which prevents issues with feeding and choking.
On the other hand, the lip can be too short and not provide sufficient sealing between the nozzle and the hop-up bucking. What we try to achieve is to have an optimal length of the lip and a nice fit between the bucking and the nozzle. For that purpose we offer the EPeS nozzle with advanced geometry. Additionally, you can use an innovative design cylinder head, allowing you to use a longer nozzle.