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PolarStar Airsoft JACK V2 M4 / M16 Electro-Pneumatic Gearbox Conversion Kit

ID: 54142 (GB-PS-Jack-SJV2-M4)
5.0 stars, based on 4 reviews
PolarStar Airsoft JACK V2 M4 / M16 Electro-Pneumatic Gearbox Conversion Kit
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The manufacturer of this product enforces a strict minimum advertised price (MAP) policy which excludes this product from any additional discount coupon codes. This item, however, may qualify for free shipping.

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The JACK™ system was designed to answer the demand for an affordable, high performance HPA (High Pressure Air) conversion for AEG's. The system is a drop-in cylinder replacement that is universally compatible with a wide range of gearbox versions that have center-line nozzles.

Similar to its sister product, the F1, it replaces the original gearbox components with a programmable pneumatic system allowing for higher performance and greater reliability over a gear driven system. Although economically priced, JACK™ still retains the same performance and quality you have come to expect from PolarStar products.

JACK™ has only 1 moving part, the nozzle, which acts as its own poppet valve which is piloted by the solenoid. With the exception of the poppet being integral to the nozzle, the valve is similar to the poppet valve used in the previously released Fusion Engine™ and is what gives JACK™ its signature muzzle report. The system itself only has 6 parts and can be completely disassembled by hand in a matter of seconds so the system is very reliable and easy to maintain.

Just like all other PolarStar HPA conversions, JACK™ also allows for easy velocity adjustment. Using a standard M4 as an example, velocity can be adjusted from below 280fps and up to approximately 500fps with a .20g BB. This can be done simply by adjusting input pressure and poppet dwell to fine tune your rifles velocity in increments of just a few FPS at a time. Maximum velocity potential of the system will vary depending upon the barrels length and tightness of the bore. Longer and tighter barrels will yield a higher velocity while shorter or wider barrels will be yield a lower velocity.

As with all of PolarStar's electro-pneumatic conversion kits, you can quickly change and adjust key functions of JACK™ via the on-board FCU (Fire Control Unit) which is no bigger than an AEG's MOSFET and can easily fit inside of a rifles battery compartment along with a small Li-po battery. Using the FCU's five position joystick and LCD display you will be able to easily and precisely adjust such functions as the systems cyclic rate, fire modes and poppet dwell on the fly.

Although efficiency was not a critical requirement during development, JACK™ does boast some highly respectable figures in this category. This is made possible by is compact and intelligently laid out design which minimizes dead volume resulting in better air flow, faster response and less air used per shot. As a result JACK™ is considerably more air efficient than a bone stock Fusion Engine™ when operating in the same velocity range.

HPA system not included


  • Designed, manufactured and built in the U.S.A.
  • Assembled from CNC machined aluminum components with high performance delrin nozzle
  • Universal cylinder design is compatible with numerous gearbox versions
  • Optimized flow profile, firing point and flow path promotes superior shot consistency and accuracy
  • Capable of functioning in damp and sub-freezing climates without affecting performance or reliability
  • User selectable Semi/Full Auto, Semi Auto Only and Variable Burst modes
  • Independently adjustable velocity and cyclic rate
  • Auto Switch mode allows for proper selector configuration for specific models
  • Easy to use Fire Control Unit (FCU) with LCD display and five position joystick
  • Instantaneous trigger response. Faster than an AEG with a Li-po
Material: Aluminum / Delrin
Compatibility: Tokyo Marui Spec Version 2 Gearboxes
Included Nozzle Type: M4 / M16 Series
Rate of Fire: 1 - 30+ RPS (Adjustable)
Muzzle Velocity: 500 FPS w/ .20g 6mm BB @ 120 PSI
Fire Modes: Semi / 2 - 9 Round Burst, Semi / Full Auto, Semi Only
Power Source: HPA (High Pressure Air via Remote Air Rig)
FCU Battery: 7-10VDC w/ JST Connector
PSI Operating Range: 40 PSI - 130 PSI (Do NOT exceed 130 PSI, otherwise you may damage the internals)
Package Includes: Pre-Assembled JACK Conversion Kit
Battery: 7.4v-9.6v NiMH or Lipo (Not included).

Manufacturer: PolarStar Airsoft

Required for Operation:Complete TM Spec AEG rifle with gearbox, Regulated Air Rig, HPA Tank, Battery (Sold Separately)

Installation: JACK™ will be installed into the shell of your AEG's gearbox. The only parts which you need to retain from your gearbox is the trigger w/ spring, safety assembly and selector components. Retain the original spring guide for models which require that the stock be secured to the gearbox and not the receiver.

Compatibility Disclaimer: The Version 2 - M4/M16 kit is compatible with most TM Spec AEG's in that rifle series. This kit is compatible with other TM Spec rifles which use a Version 2 gearbox with the traditional open contact trigger switch. In most cases only a model specific nozzle is required to install the system into another model (i.e. M4 to MP5). If your rifle has an electronic micro switch (i.e. Ares Amoeba) you will need to purchase the kit for that specific model series which will include a different switchboard.

Disclaimer on High Pressure Air (HPA) Systems:Only HPA or Nitrogen should be used with the JACK™ system. CO2 and Propane cannot be used. Using liquid propellants such as this can result in damage to the system.

HPA Tanks are a safe and effective source of power though there are some precautions you must follow. Please follow these proper precautions when using HPA systems:

- NEVER put oil in the fill valve of the tank, or else the tank can combust on refill and serious injury can occur. Lubrication is not necessary in HPA systems.
- ONLY allow properly trained professionals to fill your HPA tank.
- ALWAYS double check your Regulator pressure. Never raise the regulated pressure above 120 PSI
- Make sure to have your tank Hydro-Tested when necessary. (Usually 3-5 years from date marked on tank, depending on make and model)
- Be sure to properly transport your HPA tank. Store in a safe, secured place when in a vehicle, and be sure to stow in a bag or tank cover when in use. Avoid dropping the tank on hard surfaces as this can seriously damage the tank and lead to failure.
- Always turn off the tank and bleed the air line when you are done. This will ensure a longer tank and system lifespan.

4 Customer Reviews

(Write a review)

by Nick D. on 03/29/2017
"Love this engine!!! Super simple install, The FCU is the easiest i have ever used, AND the fact there is so much you can customize.. Definitely buying another for a DMR build soon!
by Kathryn G. on 05/20/2016
"AMAZING AMAZING AMAZING!!! I personally had a rough time with hpa guns when I purchased the valken v12 (which is not good) and the nozzle was REALLY long!! So I returned it and 2 1/2 weeks later this baby arrived its the bet thing I have boughten so far yes boughtens a word.

Its FREAGIN polarstar
You look pretty awsome
Own scrubs
REALLY light
Super strong and air efficient
Built to last
Makes you look tacticool

When your shooting you better have bbs on speed dial cuz this thing RIPS through bbs I went through a midcap mag in almost a minute shootin only semi.
by Michael F. on 08/03/2015
"I got this pretty much the first batch and Its preformed pretty awesome. Here are some pros and cons. or mostly Pros..

Fast really fast I run mine at a modest 25 30rps and it feeds and shoots great.
Ultra efficient. I shot 1500 2000 bbs and I still had almost 2000 psi in my 68 tank on 2800 psi fill. So I would assume 5000 shots from a 68 3000 psi fill.
FPS Is AWESOME. Through my Xcoretec im at 395fps with a .25 and 370fps with a .30 My choice of bb is .30 For Jack and its deadly accurate and really sends a .30 nicely.
Not easy to drop in like they say in ALL gear boxes. My Choice was a G&P and I had to dermal out 3 spots to get the fcu wire to sit not pinched.
Also getting the gear box to close with the trigger spring flying out the Spring guide falling all over the Air line out the bottom when it wants to be straight not curved down and the fcu wire to also lay out the fresh cut hole out the back is a task. 2 hands were required at that point it wasn't to bad.
Some times full auto quit working on me. I would go from semi to full and get semi on full.. Its a crap shoot but seams like its working now but im not sure why it works and sometimes wont.
I have shot this about 10,000 rounds 2 games and its still working well other then the small mishaps.
I would HIGHLY recommend getting some kind of LIGHT trigger spring set up like a speed trigger. There is NO reason to have a insanely tite trigger when you dont need it to activate the small switch. I didnt have a new lighter spring and the G&P one is way way to strong and hard to keep in place while trying to close up the box.
all in all its an Incredible item and I can tell you this calling Polarstar is almost like calling buddy's they are there to help and fix what they can. USA built. I have another in my cart right now.

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