The FX Impact MKII Is Now Upgraded With Power Plenum

The FX Power Plenum is the newest upgrade to the FX Impact!

The company explains that the demand for airgun slug shooting has created the need for a larger plenum on the Impact. This new addition opens up the ability for the Impact to shoot an even wider variety of airgun projectiles (especially airgun slugs) at optimum velocities.

Power Plenum

What’s A Plenum?

The plenum in an airgun is the chamber of compressed air located between the regulator and the valve.

The regulated air it contains is released when the trigger is pulled. The air then rushes through the valve opening and propels the pellet or slug down the barrel.

The combination of pressure and volume of air released is a the key factor in achieving power in a PCP air rifle. Generally-speaking, the larger the plenum, the more power can be generated by the airgun. Hence the larger FX Power Plenum. You can read more background in Bob Sterne’s article.

FX Airguns has spent the last two years designing and experimenting with different solutions to add this needed volume allowing the Impact to shoot different and heavier projectiles. This has been achieved while also successfully maintaining the Impacts ability to shoot pellets at lower velocities.

Power Plenum

Other Modifications:

In addition to adding a larger plenum, a significant amount of parts inside the Impact were also changed. This was to ensure that the internal working mechanisms could not only handle the demands shooters would place on it, but to make sure the Impact would still shoot standard weight pellets.

In addition, the fine tuning options the FX Impact has always offered have been kept in place. This was also done making sure these many changes and parts could be applied to existing Impacts that are owned by customers already.

Power Plenum

FX Impact MKII with Power Plenum Benefits:

1. Higher velocities can be obtained. For instance, the standard .22 caliber FX Impact previously achieved 32 Ft/Lbss. of muzzle energy with standard pellets. With the FX Power Plenum added to the .22 caliber Impact, though tuned from the factory to still shoot at 32 Ft/Lbs, you can now adjust the gun and shoot heavier slugs and obtain as high as 60 Ft/Lbs of Muzzle Energy.

2. Lower velocities still available. While the higher powers are now achievable, often shooters want lower power to for different shooting situations (or to simply extend shot count). Thanks to the internal part changes to the Impact, the lower velocities can still be achieved.

3. Increased shot count per fill. With the FX Power Plenum, the 75 shots per fill that the standard tuned .25 caliber Impact previously achieved, is now increased to 110 shots per fill. That’s just one example.

4. Lower regulator pressure required. You get the same velocity result with lower regulator pressure due to the FX Power Plenum. Lower pressure will also result in less wear and tear maintenance to your rifle, says FX Airguns.

The FX Impact MKII with Power Plenum is currently shipping to FX dealers around the world. The company says that US-based FX Dealers should have their first shipment of Impacts with the Power Plenum by the second week of January.

.35 Caliber FX Impact Update:

For those anxiously awaiting the .35 caliber FX Impact will be pleased to know that with the addition of the FX Power Plenum, the Impact is now fully ready for this exciting hunting caliber.

The .35 caliber Impact is in its final stages of testing and will soon go into production. Full details to follow, but the .35 caliber Impact will be a 150+Ft/Lbs hunting rifle!

Updating Existing FX Impacts:

FX Airguns has made every effort to make sure that the FX Power Plenum and its corresponding new internal parts can be added to previous generations of the FX Impact. Contact an authorized FX dealer for more information and timeline for availability.

Here are the details for US based customers that would like to upgrade their FX Impact:

The addition of the FX Power Plenum involves many internal part upgrades and changes. You will need to send your gun either to FX Airguns USA or to an authorized FX Airguns warranty dealer to have the upgrade to keep your warranty intact.

Power Plenum

Any MKII Impact can be upgraded to the FX Power Plenum for a flat fee of $300. This covers parts, service, and shipping back to the customer. Owners of previous generation Impacts can still be upgraded but will require additional parts & service depending on the generation Impact you have.

Anyone who has purchased a new FX Impact within the previous 60 days (or those who have recently had their MKI Impact upgraded to MKII by FX USA) will have this rate reduced. Contact FX USA for more details.

Customers who have previously inquired about having an Ernest External Plenum or who are on the MKI to MKII upgrade list will be contacted by the company about this full upgrade.

There is a handful of approved FX Impact owners who may be able to upgrade their rifle themselves (you most likely already know who you are). This is not recommended but on a case by case scenario may be considered by contacting FX USA. The cost of just the Power Plenum parts is $175.

For More Information:

Either contact your favorite FX Dealer to enquire or contact FX USA directly by emailing

You can also call FX USA at 1-866-639-0772, but keep in mind initially upon release of this information, many will be trying to contact FX USA. An email is the best way to ensure the quickest response as FX USA will be responding to customers in the order the emails are received. Please provide which generation of Impact you have and a phone number so that FX USA can easily contact you.

FX Impact Mk II Air Rifle