Overview
The PS90 SBR Options give you three clear paths: purchase a fully assembled short-barrel rifle, send in your factory PS90 for a compliant conversion, or build your own with DIY components. Whether you’re filing a Form 1 or prefer a turnkey Form 4 solution, FN Specialties delivers the parts, services, and engraving needed to build it the right way.
Complete PS90 SBR Rifles (Form 4)
- PS90 SBR by AOK: Built on a factory FN PS90, converted by Armory of Kings and engraved for compliance. Includes a CMMG 10.4" barrel and muzzle device, with optional upgrades.
- XF50 SBR Build: Features the XF50 Tri-Rail upper receiver, CMMG 10.4" barrel, and muzzle device. Transferred as a complete SBR with proper engraving.
Conversion & Kit Options (Form 1)
- PS90 SBR Conversion Service: Send in your PS90 for installation of a CMMG 10.4" barrel and thread adapter. Engraving applied per your approved Form 1 registration.
- XF50 Receiver Kit: Includes XF50 upper receiver, CMMG 10.4" barrel, thread adapter, and muzzle device. Requires approved Form 1 and engraving prior to assembly.
DIY Components
For experienced builders filing their own Form 1, individual parts are available for custom SBR projects. Proper engraving and ATF approval are required before installation.
- Factory shroud removal tool
- CMMG 10.4" barrel
- CMMG 1/2x28 adapter
- P90 style muzzle device
- KeyMo / KeyMicro muzzle device
Compliance
- All NFA rules apply
- Form 1 builds require personal engraving matching the applicant’s name and address
- Complete builds are engraved and transferred on a Form 4
- Do not install SBR components until ATF approval is received