FX Airguns Bull Barrel Kit STX (Panthera, Dynamic, King)

FX Bull Barrel Kit: stability-focused setup for slugsHuub Andriessen

The Bull Barrel Kit STX is a serious upgrade, but let me be straight with you: if you're plinking at short range or shooting standard pellets at moderate power, you won't feel much difference and it simply isn't worth the investment. Where this kit genuinely earns its place is in slug shooting at longer distances or when running your Panthera, Dynamic, or King at higher power levels, the 20 mm solid steel housing adds meaningful front-end mass that noticeably reduces muzzle climb and keeps your sight picture steady for faster follow-up shots. The precision-ground STX liner fit inside that housing is what separates this from a basic heavy barrel. My tip: if you're shooting .22 slugs specifically, make sure you order the correct liner variant, the Superior Heavy Liner included in the .22 kit is tailored for slugs and makes a real difference in consistency.

FX Airguns Bull Barrel Kit STX For FX Panthera, Dynamic, King

The FX Bull Barrel Kit 700 mm is built to add mass and stability to FX air rifles equipped with a Dynamic MKI or Dynamic MKII block like the FX Panthera, FX Dynamic and FX King. The solid steel barrel housing is made of a massive 20 mm diameter tube, increasing weight toward the muzzle and maximum stability with no flex. This added mass helps reduce muzzle rise during the shot cycle, allowing the shooter to stay on target and maintain a stable sight picture for faster follow-up shots.

The barrel assembly uses a screw-in design at the rear, with the STX liner system positioned inside the housing. A standard ½” UNF thread at the muzzle end allows the use of a moderator or muzzle brake, depending on the setup. The design is compatible with current FX Dynamic platforms as well as earlier models such as the FX Panthera, FX Dynamic and FX King.

Depending on caliber, the kit is supplied with a specific STX liner configuration. The .22 (5.5 mm) version includes a Superior Heavy Liner for slug use, while the .30 (7.62 mm) version features a Superior Liner. The STX Liner inside the housing is precision ground to achieve an accurate and tight fit in the steel housing. The liner system remains interchangeable, allowing configuration changes when required.

The increased barrel mass and rigid construction support more controlled shooting behavior, maximum stiffness and stability, particularly at higher power levels or when using heavier projectiles.

Key features:

• Solid steel barrel housing, 20 mm diameter
• 700 mm barrel length for extended velocity and stability
• Added front-end mass to reduce muzzle climb
• ½” UNF thread for moderator or muzzle brake
• Compatible with FX Dynamic and Dynamic MKII blocks
• Fits platforms such as FX Panthera, FX Dynamic and FX King
• Interchangeable STX liner system

Application: Developed for serious shooters looking for maximum stability and reduced movement during the shot cycle, particularly when shooting slugs or at longer distances.

We do not ship these items to Sweden, USA or Canada