In the ever-evolving world of precision air rifles, few manufacturers have pushed the boundaries of innovation quite like Swedish company FX Airguns. Their latest masterpiece, the FX Impact M4, stands as a testament to their commitment to excellence and technical innovation. This review delves deep into what makes the Impact M4 not just another PCP air rifle, but potentially a game-changing platform that sets new standards for what modern air rifles can achieve.
Table of Contents
Design and Build Quality
Overall Construction
The FX Impact M4 immediately impresses with its bullpup design, which manages to pack extraordinary capability into a compact package. The standard model, featuring a 600mm (23.62″) barrel, maintains an overall length of just 34 inches while weighing in at a modest 6.85 lbs. The sniper variant, with its longer 700mm (27.55″) barrel, extends to 39 inches and weighs 7.15 lbs – still remarkably manageable for its capabilities.
Material and Build Improvements
One of the most notable improvements in the M4 over its predecessor is the new rigid top plate and scope rail system. The significantly thicker top plate enhances both shooting experience and performance, providing a more stable platform for precision shooting. The innovative rail system features an 11mm dovetail machined into the top, upon which rides a removable Picatinny rail with 30 MOA compensation. This design allows shooters to customize their optics setup for optimal eye relief and shooting position. Currently, FX Impact M4 is one of the best PCP air rifles on the market.
Ergonomics and Handling
The M4’s ergonomics have been carefully considered. The new UG1 AR-style grip and safety switch will feel immediately familiar to modern sporting rifle shooters, while the vertically adjustable rubber buttpad allows for precise fit adjustments. The forward-mounted, reversible cocking lever is particularly noteworthy, offering smooth, effortless magazine cycling that enables rapid follow-up shots without breaking position.
Technical Innovation and Performance
The Revolutionary Regulator System
At the heart of the Impact M4’s performance lies the Adjustable Match Precision MKII (AMP) regulator. This sophisticated system provides unprecedented control over the rifle’s air delivery, allowing for fine-tuning to match specific ammunition and power requirements. The inclusion of dual Wika pressure gauges – one for the air cylinder and one for regulator pressure – gives shooters real-time feedback on their system’s performance.
Power Management and Customization
The M4’s power management system is where it truly shines. The improved Power Plenum 750 system increases post-regulator volume, allowing for a wider power adjustment range without sacrificing shot count. This is complemented by:
- External micro and macro hammer spring tension adjustment
- External valve control adjustment
- Quick Tune System for nearly tool-free adjustments
- Power Block for optimized power transfer, especially beneficial for heavy slug shooters
The Innovative Barrel System
The Smooth Twist X Superior (STX) barrel system represents a significant advancement in air rifle technology. This system allows for:
- Interchangeable calibers and barrel liners
- Custom rifling twist rates for specific ammunition types
- Dual transfer ports in .22 and .25 calibers, optimized for both pellets and slugs
- Superior accuracy potential across multiple projectile types
Performance
Power
Chrony tests:
| Calibers | Pellets | FPS | FPE |
|---|---|---|---|
| .35 | JSB Match Diabolo Exact 81.02 Gr | 845 | 128.49 |
| .30 | JSB Match Diabolo Hades 44.75 gr | 870 | 75.23 |
| .177 | JSB Exact Heavy 10.34g | 900 | 18.6 |
| .25 | JSB Diabolo Exact King Heavy 33.95 gr | 875 | 57.73 |
| .35 | JSB Match Diabolo Exact 81.02 Gr | 915 | 150.66 |
| .35 | JSB Match Diabolo Exact 81.02 Gr | 877 | 138.4 |
| .22 | JSB Diabolo Exact Jumbo Heavy 18.13 gr | 940 | 35.58 |
| .177 | NSA 12.5 gr | 977 | 26.5 |
| .22 | JSB Diabolo Exact Jumbo 15.89 gr | 940 | 31.18 |
| .22 | JSB Jumbo Express 14.35gr | 1003 | 32.06 |
| .22 | JSB Jumbo Heavies 18.13gr | 863 | 29.99 |
| .25 | JSB Exact King 25.4 gr | 893 | 44.99 |
| .25 | JSB King Heavies MKII 33.95gr | 849 | 54.35 |
| .30 | JSB Exact 44.75 gr | 829 | 68.31 |
| .25 | Air Arms Diabolo Field 25.4gr | 938 | 49.64 |
| .25 | JSB Exact King Diabolo 25.39gr | 907 | 46.39 |
| .25 | Air Arms Diabolo Field 25.4gr | 897 | 45.39 |
| .25 | JSB Diabolo King Heavy MKII 33.95gr | 816 | 50.21 |
| .25 | JSB Exact King 25.39 Gr | 1100 | 68.23 |
| .30 | JSB Exact 44.75 gr | 675 | 45.29 |
| .177 | NSA Slugs 12.5 gr | 977 | 26.5 |
| .25 | JSB King Heavy Mark II 33.95 | 748 | 42.19 |
| .22 | JSB Exact Jumbo Diablo 15.89 gr | 940 | 31.18 |
| .30 | Zan Projectile 45.5 gr | 813 | 66.8 |
The Impact M4 delivers impressive power across all calibers:
- .177 caliber: 35 FPE (foot-pounds of energy)
- .22 caliber: 87 FPE
- .25 caliber: 100 FPE
- .30 caliber: 125 FPE
These figures represent maximum energy achieved with the FX Slug Power Kit installed, making the M4 suitable for everything from target shooting to medium-game hunting.
(For more on the best air rifles for hunting, see this post)
Accuracy
Accuracy tests:
| Calibers | Pellets | Distances | Groups |
|---|---|---|---|
| .177 | JSB Match Diabolo Exact 8.4 Gr | 50 yards | 3/4" |
| .30 | Slugs 67 Gr | 50 yards | 3/4" |
| .30 | Slugs 67 Gr | 100 yards | 1 1/2" |
| .30 | JSB Match Diabolo Hades 44.75 gr | 50 yards | .557" |
| .25 | JSB King Heavy Mark II 33.95 gr | 100 yards | 1" |
| .30 | Nielson Slug 47 gr. | 50 yards | one hole |
| .22 | JSB Diabolo Exact Jumbo Heavy 18.13 gr | 50 yards | one hole |
| .30 | JSB Diabolo Exact 50.15 Gr | 60 yards | one hole |
| .25 | JSB Match Diabolo Hades 26.54gr | 35 yards | one hole |
| .35 | JSB Match Diabolo Exact 81.02 Gr | 100 yards | 1" |
| .22 | JSB Diabolo Exact Jumbo Heavy 18.13 gr | 95 yards | 3/4" |
| .177 | NSA Slugs 12.5 gr | 50 yards | nickel size |
| .22 | JSB Match Diabolo Exact Jumbo Heavy 18.13gr | 50 yards | dime size |
| .25 | JSB Exact King 25.39gr | 50 yards | 3/4" |
| .22 | JSB Exact Jumbo 15.89gr | 50 yards | 1/2" |
| .25 | JSB Exact King Diabolo 25.39gr | 50 yards | 0.37" |
| .25 | Air Arms Diabolo Field 25.4gr | 50 yards | 0.47" |
| .25 | JSB Diabolo King Heavy MKII 33.95gr | 50 yards | 0.71" |
| .25 | JSB Exact King Diabolo 25.39gr | 100 yards | 1.34" |
| .30 | JSB Exact 44.75 gr | 50 yards | 0.557" |
| .177 | NSA Slugs 12.5 gr | 50 yards | Nickel-size |
| .25 | JSB King Heavy Mark II 33.95 gr | 100 yards | 1.5" |
| .30 | JTS Dead Center 45.06 gr | 45 yards | 5/8" |
| .30 | FX Hybrid Slugs 44.5 gr | 45 yards | 5/8" |
| .30 | H&N Slug HP II 50 gr | 45 yards | 3/4" |
| .30 | Zan Projectile 45.5 gr | 45 yards | 3/8" |
Shot Count and Efficiency
The rifle’s efficiency is remarkable, particularly considering its power output:
Standard Model (480cc cylinder):
- .177 caliber: 375 shots per fill
- .22 caliber: 270 shots per fill
- .25 caliber: 130 shots per fill
- .30 caliber: 85 shots per fill
Sniper Model (580cc cylinder):
- .22 caliber: 330 shots per fill
- .25 caliber: 160 shots per fill
- .30 caliber: 105 shots per fill
Air Management
The system operates with a maximum fill pressure of 250 BAR (3,625 PSI) and a regulator working pressure of 170 BAR. The inclusion of a male Quick Disconnect fitting makes filling straightforward and secure. It’s worth noting that while the manual mentions 300 BAR capability, this is only achievable with aftermarket carbon fiber bottles – the factory bottles should not exceed 250 BAR.
Practical Applications
Target Shooting and Competition
The Impact M4’s precision engineering makes it an excellent choice for competitive shooting. The adjustable match-grade trigger, stable platform, and highly customizable power delivery system make it particularly suited for:
- Benchrest competition at 100 yards
- Field target shooting
- Precision target practice
- Long-range shooting
Hunting Applications
The rifle’s power output and accuracy make it suitable for various hunting scenarios:
- Small game hunting
- Medium game hunting (with appropriate caliber and power settings)
- Pest control
- Field shooting
The quick-follow-up shot capability and high magazine capacity (ranging from 23 to 34 rounds depending on caliber) provide additional versatility in hunting situations.
Customization and Versatility
Caliber Options
The Impact M4 offers exceptional versatility through its caliber options:
- Standard model: Available in .177, .22, .25, and .30 caliber
- Sniper model: Available in .22, .25, and .30 caliber
The ability to change calibers through the barrel liner system adds significant value for shooters who want multiple capabilities in one platform.
Adjustment Capabilities
The level of adjustability is unprecedented:
- External hammer spring tension (macro and micro)
- Valve control
- Regulator pressure
- Power adjustment
- Trigger settings
- Stock fit and configuration
This level of customization allows shooters to optimize the rifle for specific applications and ammunition types.
Magazine System and Loading
The Side Shot magazine system offers generous capacity:
- .177 caliber: 34 rounds
- .22 caliber: 28 rounds
- .25 caliber: 25 rounds
- .30 caliber: 23 rounds
The magazine system is well-designed and reliable, with older Side Shot magazines remaining compatible with the M4 platform.
Maintenance and Support
Warranty and Service
The Impact M4 comes with a 3-year transferable warranty, demonstrating FX’s confidence in their product. The Quick Tune System makes routine maintenance and adjustments straightforward, with minimal tool requirements.
Upgradability
The platform’s modular nature allows for significant upgrading potential:
- Interchangeable barrel liners
- Different caliber conversions
- Power upgrade options
- Additional accessories through the multiple Picatinny rails
Features:
FX Impact M4 PCP Air Rifle
- FX Smooth Twist X Superior (STX) barrel system
- Interchangeable calibers and barrel liners (sold separately)
- Power Block
- Externally adjustable AMP MKII (Adjustable Match Precision) regulators
- Externally adjustable hammer spring tension with macro and micro adjustments
- Externally adjustable valve control
- Quick Tune System for virtually tool-free adjustments
- 250 BAR (3,625 PSI) max. fill pressure
- Max regulator working pressure of 170 BAR
- Equipped with improved 75cc Power Plenum 750 – allowing for an even wider range of power adjustment
- .22 and .25 cal M4’s feature Dual transfer ports – one optimized for pellets, one for slugs
- Male Quick Disconnect fitting
- Shroud is threaded 1/2×20 for moderator
- Forward mounted reversible sidelever cocking
- Picatinny/Weaver optics mounting rail with 30 MOA compensation rides on 11mm dovetail allowing further customization to meet every shooters need
- Picatinny accessory rails below cylinder and on each side of the forearm
- New Quick Set Trigger – Adjustable match trigger
- Wika dual pressure gauges: one for air cylinder pressure, one for regulator pressure.
- Height adjustable rubber buttpad
- FX UG1 AR15 style grip
- AR15 style manual safety
- Redesigned Side Shot magazine capacity*: 34 rds. in .177, 28 rds. in .22, 25 rds. in .25, 23 rds. in .30
- Maximum muzzle energy **:
- 35 FPE in .177
- 87 FPE in .22
- 100 FPE in .25
- 125 FPE in .30
- Includes one side-shot magazine, FX moderator, and 3 year transferable warranty
* – Older Side Shot magazines are compatible with the M4.
** – Max Energy achieved with FX Slug Power Kit installed.
600mm (23.62”) Barrel, Standard Models:
- Available in .177, .22, .25 and .30 cal.
- Removable 480cc carbon fiber air cylinder
- Overall length of 34”
- Weight: 6.85 lbs.
- Shots per fill: 375 in .177, 270 in .22, 130 in .25 and 85 in .30
700mm (27.55”) Barrel, Sniper Models:
- Available in .22, .25 and .30 cal.
- Removable 580cc carbon fiber air cylinder
- Overall length of 39”
- Weight: 7.15 lbs.
- Shots per fill: 330 in .22, 160 in .25 and 105 in .30
Pros and Cons
| Pros | Cons |
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Conclusion
The FX Impact M4 represents the pinnacle of current PCP air rifle technology. Its combination of innovative features, unprecedented adjustability, and exceptional performance sets it apart in the market. While it may require a significant investment and time to master, the platform offers tremendous versatility and capability that can serve everything from casual target shooting to serious competition and hunting.
The rifle’s modular nature and upgradeability help future-proof the investment, while its robust construction and comprehensive warranty provide peace of mind. For the serious air rifle enthusiast who demands the ultimate in precision and adjustability, the Impact M4 delivers in spades.
Whether you’re a competitive shooter looking for a winning edge, a hunter requiring versatility and reliability, or simply an enthusiast who appreciates engineering excellence, the FX Impact M4 offers a compelling package that pushes the boundaries of what’s possible in a PCP air rifle.
The combination of Swedish engineering excellence and practical shooting requirements has resulted in a platform that not only meets current demands but sets new standards for what users can expect from a modern PCP air rifle. While it may be more than some shooters need, for those who can utilize its capabilities, the Impact M4 represents the current state of the art in air rifle design and performance.
