FPS Retaining O-Ring for Nozzle (CITY2)

The FPS spring from 85 m/s was calibrated on rods from 363 mm e gearbox con cilindro type D (for rods 301 a 400 mm).
Of course, with shorter or longer barrels the performance will decrease or increase, so you will move on to the harder or softer calibration.
In the calibration process, the thickness due to the bearings of the spring guide and the piston head was not taken into consideration, therefore, with the same initial conditions, an increase in performance of approximately 2.5 m/s for each bearing.
The FPS spring is 100% Made in Italy and was created in collaboration with leading companies in the sector.