OMEGA Valve Mod. 4 (MPX, 9mm)

*We will be the only dealer with these for the initial batch aside from a small number available from J Bennett*

This product is in late stages of development and production is expected to begin in September. This page exists to serve as a source of information and a means to register for in-stock notifications. We expect extreme demand and will do what we can to prepare to accommodate our customers. 

The OMEGA Valve Mod. 4 is the world’s first hand-adjustable gas regulator for the Sig Sauer MPX weapon system. It is a drop-in component, able to be installed at the user lever in minutes.

Mod. 4 features an elongated body that allows the knob section to clear the end of the MPX receiver’s top rail, allowing the user to adjust the regulator without removing the barrel or the use of wrenches or other tools.

Note: to access the knob, the user must slide their handguard forward, modify their existing handguard, or purchase an aftermarket handguard that features an adjustment window (similar to those found on MCX handguards).

Other features:

• Five discrete positions, with indicia found on the knob to indicate the current position. The following descriptions are based on internal testing of a 4.5″ MPX-K with an Apparition Instruments Nano/CAT TSFX attachment setup and OEM Recoil  Springs.

• • Off (ø) – Either supersonic or subsonic ammunition. 100% eliminates ejection port sound signature.
  • 2 – high back pressure silencers, likely shooting supersonic ammunition.
  • 3 – high back pressure silencers, likely shooting subsonic ammunition.
  • 4 – low back pressure silencers, likely shooting supersonic ammunition.
  • 5 – low back pressure silencers, likely shooting subsonic ammunition.

• The various positions have nearly identically-sized gas ports. The internal geometry of the ports delay the timing of the gas entering the expansion chamber. This eliminates the need to over-restrict the gas from the barrel’s gas port and helps  mitigate the risk of erosion on the gas regulator.
• Various geometric features to allow the user to force the valve to turn in the event that it becomes carbon locked.
• An optional O-Ring to assist in the use of extremely low pressure ammunition with extremely high flow silencers.

In a departure from other JBD products, the OMEGA Valve Mod. 4 does not utilize a jet screw system. 9mm ammunition does not appear to offer enough gas to need a jet screw system. Just choose a position between 2-5 and rock n’ roll!

This valve is confirmed to function in both the 8″ Gen 1 upper as well as the 4.5″ Gen 3 upper. We have not tested other configurations, but we are of the belief that it should be compatible with all OEM configurations of the MPX. We have not evaluated the use of these products with aftermarket barrel assemblies and have no intension to do so. We will update this product description if a brave customer figures it out, but for safety reasons we expressly advise against trying this gas regulator in any barrel configuration outside of Sig Sauer’s OEM catalog.

Material and Coating – as of 07/27/26, materials and coatings are still being evaluated for durability, as the MPX system is notorious for erosion issues within the gas block. So far, we are leaning toward continuing to use 17-4PH Stainless Steel, but Inconel 625 is on the table. The coating will be black and lubricious.

Proudly made via Direct Metal Laser Sintering by MK Machining in Missouri.

What to expect:

The above descriptions are given with regard to the 4.5″ MPX-K. As we have seen in the development of the 300BLK line of products, dwell time makes a massive difference in performance. This valve is tuned to the bleeding edge of performance with high flow silencers on the 4.5″ barrel. Some low pressure ammunition will not function without a silencer with adequate back pressure and/or reduced-power recoil springs. Longer barrels, such as the 6 inch, 8 inch, and [presumably] the 16 inch will have a wider envelope of what they will and will not eat with this valve.

It is possible to rotate this valve too far, beyond the off position or position 5. We recommend installing the valve in a safe and empty firearm without the presence of ammunition and simply playing with it to get a feel for it. The positions are quite tactile, and if you rotate beyond the end it’s easy enough to back track into position. No, it will not rotate under recoil or from a stray branch in the woods.

There is exactly 0.30″ of clearance between the end of the valve and the tip of the muzzle on the 4.5″ barrel. Not all combinations of muzzle device and silencer adapter will fit. We recommend the Apparition Instruments Nano Mount and the CAT TSFX HUB Adapter, simply based on our testing.

As with all JBD products, this device was designed to be used with a suppressed weapon system. This product should allow the 4.5″ MPX-K to cycle and lock back in the unsuppressed state with supersonic ammunition and full power, duty-grade subsonic ammunition.

Disclaimer: Sig Sauer®, MPX®, and MCX® are trademarks of Sig Sauer, Inc. J. Bennett Designs, LLC is not affiliated with or endorsed by Sig Sauer, Inc. OMEGA Valve is an independent product compatible with the Sig Sauer® MCX® and MPX® platform.