CGS™ - CO2 Gas Stock
CGS™ - CO2 Gas Stock

CGS™ - CO2 Gas Stock

Regular price $332 now $325

If you are someone that has always wanted to have the performance and versatility of an HPA system but just couldn't bear the thought of being tethered to an airline or having a tank screwed into the back of your rifle, then the CGS™ was designed specifically with you in mind. Externally the CGS™ is manufactured using a real Milspec buffer tube blank which has been modified to conceal an adjustable regulator and CO2 cartridge which allows you to run your HPA system while retaining the same realistic appearance and the use of traditional Milspec buttstocks.

Its integral regulator shares the same internal design as PolarStar's other compact regulators and delivers performance on par with systems twice its size. This regulator has an output pressure range of 40-130psi which is easily adjusted using a 3/32 allen key but can be locked out using a standard chrono zip tie which blocks the adjustment screw. Additionally, if you want to get a little more "omph" out of the regulator, you can install the High Pressure Spring (p/n 10000692)* which boots the maximum output pressure to approximately 200psi.

This regulator is coupled with a removable CO2 insert which is easily installed by sliding the insert into the back of the buffer tube and screwing it into the regulator's ASA threads before being secured with a set screw. This modular design makes the CGS™ a very versatile system since you are able to swap between two available CO2 Inserts giving you the ability to use either traditional 12g CO2 cartridges or the magnum sized 33g cartridges (p/n 10000332)* for even more shot capacity.

These inserts feature an integral expansion chamber, anti-siphon system, 5 micron filter and check valve to prevent liquid CO2 from entering the regulator regardless of the rifle's orientation and therefore safeguarding the system from any spikes in pressure. As an added benefit, the internal check valve also prevents gases from escaping the expansion chamber while switching out cartridges so as to conserve as much CO2 as possible when performing a "combat reload" and allowing several full-power shots even while when the CO2 cartridge has been removed.

The CGS™ can be used with any of the PolarStar cylinder conversion kits such as the F2™, F1™, JACK™ or Kythera™ and is compact enough that it can also be used with other similar HPA cylinder systems on the market. This system is available with two different output configurations depending on the design of the rifle you wish to convert.

The Type 1 is designed for use with AEG receivers that accept 1-3/16"-16 threaded buffer tubes such as the G&P R3 series. This is where the buffer tube itself threads into the receiver. (Modification of the gearbox is required)

The Type 2 is designed for use with traditional TM Spec M4 series AEG receives. This is where the buffer tube slides onto a stock tail on the back of the receiver and is secured by a bolt. (Modification of the receiver and gearbox is required)

In order to offer the most realistic experience possible, the CGS™ buffer tube is machined from the same blank, using the same processes, and follows the same specifications as a Milspec buffer tube. This means the CGS is compatible with all Milspec AR stocks, but may not be compatible with some AEG stocks due to the lack of standardization between manufacturers. 

If there is a particular AEG stock that you would like to use and it will not fit on a standard Milspec buffer tube, please see the Universal Gas Stock. The UGS has the same CO2 options as the CGS, but in a modular configuration that has been designed to fit all Milspec stocks as well as most AEG stocks.

  • Includes CO2 insert (choice of 12g or 33g) castle nut and all mounting hardware.
  • Machined from a Milspec AR buffer tube blank.
  • Compatible with Milspec AR stocks.
  • Convertible between 12g and 33g cartridges through the use of interchangeable CO2 Inserts.
  • Average shot count using an F2™ at 1.5J w/ .28g and 6.05x380mm: 12g = ~180 shots, 33g = ~500 shots
  • Simple zip-tie lockout/tournament lock.
  • Incorporates PolarStar's proven compact regulator design which uses only 2 o-rings, promoting reliability and ease of maintenance.
  • Not compatible with Fusion Engine™.
  • *CO2 Cartridges & HP Spring Not Included


Min Output Pressure 40 PSI
Max Output Pressure 130 PSI  (~200 PSI with HP Spring, p/n 10000692)*
Max Input Pressure 900 PSI
Outputs Interfaces w/ Airline (6mm OD x 4mm ID)
Warranty Information 1 Year Limited Warranty