The Franklin Armory F17-X Upper Kit (brand part no. 0040075BLK) brings the .17 Winchester Super Magnum cartridge to the AR platform with a 16-inch barrel built around Franklin Armory’s Osprey Defense slim gas-piston system. Unlike a direct-impingement upper, this piston system automatically adjusts for suppressed or unsuppressed shooting with no manual regulation needed, keeping the action running clean and reliable across both configurations. The barrel is cut with a 1:9 twist rate to stabilize .17 WSM’s fast, flat-shooting projectile, and the muzzle is threaded 1/2×28 for a compensator or suppressor. A 15-inch M-LOK handguard with an integrated barrier stop gives builders room for accessories, and the upper receiver is machined from hardcoat anodized aluminum for durability. Set up to run 10-round magazines and ship optic-ready, this upper kit is built for AR shooters who want a genuinely rimfire-fast, low-recoil platform without leaving the AR-15 ergonomics behind.

Key Specifications

• Chambered in .17 Winchester Super Magnum.
• Barrel measures 16 inches.
• Runs Franklin Armory’s Osprey Defense slim gas-piston system, self-regulating for suppressed or unsuppressed use.
• Rifling uses a 1:9 twist rate.
• Threaded 1/2×28 at the muzzle.
• Fitted with a 15-inch M-LOK handguard with an integrated barrier stop.
• Machined from hardcoat anodized aluminum.
• Compatible with 10-round magazines.
• Ships optic-ready.

Frequently Asked Questions

Does the gas system need adjustment for a suppressor? No, the Osprey Defense slim piston system automatically self-regulates for suppressed or unsuppressed shooting.

What magazines does this upper use? It’s set up to run 10-round .17 WSM magazines.

Does this kit include a lower receiver? It’s an upper kit built to install on a compatible Mil-Spec AR lower receiver.

Buy the Franklin Armory F17-X 16-inch Upper Kit, .17 WSM, 10-Round, Black

Bring a fast, low-recoil .17 WSM platform to your AR build. Order it through our Franklin Armory lineup of gun accessories and parts, and we’ll get it ready to ship as soon as it’s available from our Lubbock, Texas gun shop.