Product Overview
For cylinder conversion systems numbers are assigned to the nozzles instead of using the rifle model. This is because the nozzle length can vary between the same gun model when made by different manufacturers. This can be from the manufacturer designing the rifle differently, or from the thickness of the gearbox shell affecting how far from the hop-up chamber the cylinder sits. Therefore one nozzle length may work in different rifle models but not necessarily work in the same model from a different manufacture. For example, a standard MP5 could require any of 4 different nozzle lengths depending on the manufacturer.
For this reason numerous different nozzle lengths are produced to provide compatibility for a wide range of replicas. For a list of replicas which have measured and calculated the compatible nozzle length, please visit Polarstar's Help Center. Once you determine what number nozzle your replica requires, that number is universal across all engines that use the numbered nozzle system (excluding some model specific Kythera systems).
If your gun is not listed, a recommended nozzle length may calculated by measuring your original gearbox and nozzle. Using a set of calipers and following the diagram HERE, measure these specific areas of the gearbox and input them into the following formula. Please note that measurements need to be in thousands of an inch (0.001").
F2 Centerline Nozzles: TIP = F + B - (A/2) + .293
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