ASG B&T USW A1 GBB Pistol Review – Dual-Power Gas & CO2, Tactical Precision for CQB

The ASG B&T USW A1 is a dual-power GBB pistol compatible with both gas and CO2, but it’s more than just a conventional airsoft gun – it’s a true game-changer. Combining the compact portability of a pistol with the stability of a short-barreled PDW, the USW A1 faithfully replicates the Swiss B&T USW (Universal Service Weapon).

The B&T USW was designed for law enforcement and special forces, aiming to enhance accuracy without compromising handgun-like portability. Its folding stock and red dot sight enable rapid target acquisition and control, even during fast-paced engagements.

ASG, licensed by B&T, released the USW A1 GBB. Maintaining the original proportions, ergonomics, and tactical features, ASG implemented a 1913 Picatinny rail instead of mounting the Aimpoint directly as on the real firearm, giving players more options for onboard red dot sights.

The result? A pistol that can serve as a primary weapon in CQB scenarios, or as a sidearm suitable for marksmen.

Performance & Features

ASG focused on replicating the precision and stability required by law enforcement in compact engagements. The USW A1 adopts the same KJ System used in the ASG Shadow 2, renowned for accurate shooting:

1. Dual-Power Compatibility – Supports both gas and CO2 magazines.

2. TDC (Top-Dead-Center) Hop-Up System – Ensures consistent backspin by evenly applying downward force. The adjustment wheel in the middle of the hop-up chamber allows intuitive, precise tuning with a flat-head screwdriver. Hop-up can be adjusted after removing the slide assembly.

3. Realistic Recoil Cycle – Fully open chamber design produces clear recoil, cushioned by a return spring block to emulate real firearm stability.

4. Lightweight & Durable – Upper receiver and slide made of 6061 aluminum; reinforced polymer frame and stock tube; impact-resistant internal components.

5. Tactical Concept – Features a full-length 1913 rail, bottom rail, and reverse 14mm threaded outer barrel. Compatible with a wide range of tactical accessories.

6. Two Magazine Options × Two Power Sources:

   ■ Standard CO2 Magazine (26 rounds) – Balanced capacity for general use.

   ■ Standard Gas Magazine (26 rounds) – Balanced capacity for general use.

   ■ Extended Gas Magazine (50 rounds) – Ideal for suppressive fire or using the USW A1 as a primary weapon.

   

This isn’t just a cosmetic replica – ASG aims for functional realism that meets practical tactical demands.

Disassembly & Maintenance

Slide Removal

Remove the magazine, pull the slide rearward to align with the takedown notch, push out the slide pin, and slide the assembly forward to separate.

Hop-Up Adjustment

After removing the slide, use a flat-head screwdriver to adjust the hop-up: tightening increases downward pressure; loosening reduces it.

※Pro Tip: The hop-up adjustment is hidden; always adjust before reassembly to avoid repeated disassembly.

Inner Barrel & Hop-Up Bucking Replacement

After removing the slide, take out the recoil spring assembly and the outer barrel (including inner barrel and hop-up unit). Remove the outer barrel assembly, knock out the copper pins to separate the inner barrel and hop-up unit.

Unscrew the two screws on the hop-up unit to replace the inner barrel and bucking.

※Advanced Tip: Some technicians wrap the bucking with Teflon tape for improved air seal.

Nozzle Set Removal

After removing the slide, simply loosen and remove the single hex screw located at the end of the slide (while gently pressing on the nozzle to prevent the sudden release and loss of the nozzle spring). This will allow you to easily lift it out.

Magazine Release Button Replacement

After removing the slide, from the top of the frame, locate the silver Phillips screw securing the magazine release. Loosen and remove it along with the U-shaped spring and retaining plate. Hook out the R-shaped spring, then the magazine release can be removed.

※Reassembly: Insert the long end of the R-spring first, then align the other side while securing the Phillips screw and plate. Lock the screw two-thirds of the way, then press the short end of the R-spring into position and tighten fully.

※Fun Tip: We tried swapping the magazine release button from the ASG(KJ) Shadow 2 GBB pistol onto the USW A1, but the central groove was slightly shorter, preventing the R-shaped spring from seating into the magazine release button. While this is a bit unfortunate, a minor post-processing adjustment can easily solve the issue.

Trigger & Hammer Group Removal

After removing the slide, the aluminum RIS rail cover at the rear of the frame must be taken off. Unscrew the six Torx screws, then press down the ejector pin on the right side of the rail cover(a chopstick or small flat-head punch can work for this). Be sure to keep it pressed while removing to prevent the pin from springing out unexpectedly.

Remove both safety levers (Although the USW A1’s safety is not complex, its components are tightly fitted and precise.). Start with the left safety, using a small flat-head screwdriver or punch, and push the safety pin outwards carefully. Ensure not to lose the internal linkage parts (#71 & #14). The right safety must be rotated to about the 8 o’clock position, then pushed out corresponding to its notch. Loosen the small hex screws at the right safety location.

Knock out the trigger pins from left to right (note the directional textured pin). Rear pin near the grip guard: left large, right small; knock from right to left. Once done, the hammer and trigger assemblies can be removed.

※Friendly Tip (Updated 2025-08-17):

On both the ASG Shadow 2 GBB pistol and the ASG B&T USW A1 GBB, the safety lever itself does not feature a fixed locking point for the linkage parts.

Although the linkage bar has a notch, the safety lever does not secure it in place.

Therefore, when disassembling or reassembling, extra caution is required to keep track of the linkage and the small spring.

Complete Disassembly & Grip Removal

After removing the trigger and hammer assembly, knock out the long pin at the rear underside of the grip. The grip panel can then be pushed backward. Next, locate the pin at the grip guard area, knock it out, and the valve hammer assembly (including the sear and striker) can be removed from the grip. Take care not to lose any small components during this step.

At the bottom of the grip, a flat-head slot is visible. Insert a flat-head screwdriver, push and rotate to disengage the retaining tab, allowing the black locking block to be removed. Loosen the small hex screw on the left side to remove the hammer spring guide sleeve. At this point, the entire frame and grip are cleared of internal components.

Finally, remove the four Phillips screws that secure the frame to the grip, then return to the front of the frame. Loosen and remove the Phillips screw securing the trigger guard to fully separate the grip.

※Reassembly Tip: Pay close attention to the relative positions of the hammer assembly, valve hammer assembly, and trigger linkage.

Conclusion

Why You Should Own It?

From the moment I pick up the ASG B&T USW A1 GBB, disengage the safety, chamber a round, and take the shot, the entire process feels effortless and intuitive.

Its perfectly balanced ergonomics make every action—from manipulating the controls to switching safeties—flow seamlessly. Even the tactile smoothness of engaging and disengaging the safety showcases the meticulous attention to detail in its design, just like you’d expect from a B&T USW A1 airsoft pistol.

The ASG B&T USW A1 is a unique hybrid airsoft weapon.

For players who value agility, it serves as a reliable companion for both indoor CQB scenarios and as a sniper secondary.

Licensed by B&T, the gas blowback version delivers realistic aesthetics, accurate handling, and functional features. With two magazine types, two power systems, and design flexibility for both primary and secondary roles, the USW A1’s adaptability is unmatched.

Moreover, it uses the same precision system as the Shadow 2 and TS 2, yet it is lighter and more versatile. For competitive shooters, tactical players, or collectors looking for a high-performance airsoft pistol, the ASG B&T USW A1 is a must-have addition to your arsenal.

Bonus Feature:

FALCON has developed a dedicated suppressor specifically for the ASG B&T USW A1 GBB pistol. Not only is it a perfect fit in terms of size, but—where local velocity regulations allow—you can also install an extended inner barrel for improved accuracy.

The FALCON suppressor for the ASG B&T USW A1 comes with an internal stabilizer, ensuring solid barrel support even with an extended setup, effectively reducing muzzle-end vibrations.