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UGS™ - VFC HK417

UGS™ - VFC HK417

Regular price $243

With the PolarStar UGS™ (Universal Gas Stock) you can now get the performance advantage of a HPA system without needing to be tethered to a remote air rig and still retain the likeness and function of a traditional adjustable stock. The UGS™ for the HK417 follows the same internal design as the standard UGS™ for M4/M16 series rifles but features a wider regulator body to interface with the larger diameter of the HK417 and G28 receiver extension. It can be used with any of the PolarStar cylinder conversion kits which are compatible with the VFC HK417 or G28 series such as the F2™, F1™ or JACK™ and is compact enough that it can also be used with other similar HPA cylinder systems on the market.

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.

You are able to order the UGS™ for the VFC HK417 in two different configurations. The HPA (2.000") configuration is designed to accept 13ci HPA tanks and 2.000" diameter buttstocks such as the included G&P R3 or optional MCS MTA stock (shown above).

The CO2 configuration comes with a different rail that allows it to accept our 12g or 33g CO2 Inserts which makes it possible to use traditional Milspec buttstocks*. Your choice of a 12g or 33g CO2 insert is included with the CO2 models. The 33g CO2 models accept threaded CO2 cartridges (p/n 10000332) while the 12g CO2 models use the standard 12g cartridges commonly used for Airsoft and Air Guns. One can configure the same UGS for the use of either the 2.000" HPA tanks or Milspec CO2 inserts by purchasing the different UGS Stock Rails separately.

The UGS is installed into the VFC HK417 in the same manner as the original buffer tube by threading into the receiver. It does however come with the "Type 2" output cap which features the threaded shaft and barb fitting typically used with traditional TM spec receivers. It was found that this configuration worked best due to the longer receiver of the HK417 and the Type 2 output cap offering more support for the air line which bridging the distance between the HPA engine and the regulator.

Available pre-configured for either 2.000" diameter HPA tanks or our CO2 Inserts.

      The HPA configuration includes G&P R3 buttstock pictured.

      The CO2 configuration includes your choice of 12g or 33g CO2 inserts.


      • Compatible with the VFC HK417 and G28 series rifles.*
      • The UGS regulator can accept up to 900psi allowing for the use of either standard output HPA tanks as well as SLP (SLP recommended).
      • Compatible with all standard 2.000" diameter tanks and most 2.000" tank stocks used in paintball applications.
      • Milspec configuration includes your choice of 12g or 33g CO2 inserts.
      • Simple zip-tie lockout/tournament lock.
      • Adjustable length of pull.
      • Same internal design as the other compact PolarStar regulators (Micro Reg GEN2, CGS) with cross compatibility between parts.
      • The UGS™ regulator uses only 2 o-rings, promoting reliability and ease of maintenance.
      • Not compatible with Fusion Engine™.
      • HPA Tank, Castle Nut, CO2 Cartridges & HP Spring Not Included

           *Please note that only traditional Milspec buttstocks can be used with the CO2 inserts. The original HK417/G28 stocks use a larger diameter buffer tube and therefore cannot be used on the CO2 inserts. Additionally, the longer castle nut on the G28 interferes with the closing of the stock rail when the CO2 insert is being used instead of a 2.000" HPA tank. This requires that the G28 castle nut be replaced with a HK417 castle nut, which is not included with this kit.


          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