For cylinder conversion systems, PolarStar assigns numbers to nozzles instead of using the rifle model. Nozzle length can vary between the same gun model when made by different manufacturers — due to differences in design or gearbox shell thickness affecting how far the cylinder sits from the hop-up chamber. A standard MP5, for example, could require any of 4 different nozzle lengths depending on manufacturer.
Once you determine your replica's nozzle number, that number is universal across all engines using the numbered system (excluding some model-specific Kythera™ systems). A #11 nozzle works across JACK™, F2™, and other numbered systems.
Formula for Custom Measurement
If your gun isn't in the compatibility database, measure your gearbox using calipers in thousandths of an inch (0.001") and calculate:
JACK Centerline Nozzles: TIP = F + B - (A/2) - .0875
The measured tip length should be within ±0.010" of an existing nozzle to be compatible. Contact us with your measurements for custom orders.
Compatibility Chart
| # | Most Commonly Used With | Tip (in) | OAL (in) |
|---|---|---|---|
| 1 | TM M4/M16, A&K PKM, TM MP5 A/SD, ICS MP5 A/SD, G&G KAC SR-25E2 | 0.8245 | 1.677 |
| 2 | CYMA AK, CYMA MP5 A/SD, G&G UMP | 0.8625 | 1.715 |
| 3 | CA M249/MK46, A&K M249/MK46 | 0.8095 | 1.662 |
| 4 | G&G GR-25 | 1.4505 | 2.303 |
| 5 | A&K SR-25, JG SR-25, ICS SIG 550/551/552 | 0.9635 | 1.816 |
| 6 | KA FAL, TM MP5K, A&K M240 | 0.8945 | 1.747 |
| 7 | PTS MASADA, CA SCAR-L | 1.1345 | 1.987 |
| 8 | VFC SCAR-H | 1.5075 | 2.36 |
| 9 | EF/S&T TAR-21 COMP | 0.8765 | 1.729 |
| 10 | EF ARX160 ELITE | 1.4865 | 2.339 |
| 11 | CA KAC LMG, VFC MP5 A/SD | 0.7475 | 1.6 |
| 12 | LCT AK-47/74/M, LCT VSS/AS VAL | 0.8355 | 1.688 |
| 13 | A&K MASADA/ACR | 1.3465 | 2.199 |
| 14 | KA CZ 805 BREN, CG M249 FEATHERWEIGHT, A&K M60 | 1.3895 | 2.242 |
| 15 | EF/ARES G36KV/CV, JG G36 | 1.0545 | 1.907 |
| 16 | EF/S&T G36C | 1.0415 | 1.894 |
| 17 | CA AUG | 1.0045 | 1.857 |
| 18 | G&G MP5 A/SD | 0.795 | 1.647 |
| 19 | VFC/ECHO1 XCR | 1.227 | 2.079 |
| 20 | CA G36, CYMA SR-25 | 1.026 | 1.8785 |
| 21 | Elite Force/CYMA MP5K, CA SA58 | 0.923 | 1.771 |
For a full compatibility database, visit the PolarStar Help Center.
Parts and accessories ship within 7 business days. Custom HPA rifle builds take up to 45 business days (often less). Need it sooner? Contact us to check current stock.
All sales on parts and accessories are final once shipped. Defective or damaged items are covered under the KA Tech Warranty.