I have been using a 3mm shank and a 2.8mm hole in the piston for a long time! The holding force is excellent and allows you to safely download greenery! For a long time I tried to implement a hydraulic damper on the piston, but the piston did not work for a long time due to the hole in the piston nose, along which it was cut off! This idea changes the whole concept of pistons as consumables and makes it possible to quickly change the caprolon sleeve in the shank of the harpoon! Loading forces can be safely increased!