Panzer Arms AR57 Ultra Light Tactical Complete AR-15 Upper Receiver - 5.7x28mm - 16"

The Panzer Arms AR57 Ultra Light Tactical Complete AR-15 Upper Receiver converts any mil-spec AR-15 lower to fire 5.7x28mm ammunition, pairing a 16" steel barrel with a top-loading design similar to the FN P90 that ejects spent cases down through the lower's magazine well.

Note: This upper ships with a 50-round magazine. Some states restrict magazine capacity — know your local and state laws before ordering.

Features:

• 16" steel barrel chambered in 5.7x28mm, 1:8.5 FN twist
• 1/2x28 threaded muzzle with perforated muzzle brake
• Alloy monobloc receiver integrating barrel, BCG, buffer, and screws
• 8620 alloy bolt, removable for maintenance
• Aircraft-grade 7075-T6 aluminum, rated to 83,000 PSI
• 13-slot Picatinny rail over the operating handle, plus 3-slot upper and lower forward rails
• Top-loading design, downward ejection through the AR-15 magazine well
• 50-round magazine included

This upper is a straightforward path to converting an AR-15 lower into a firearm chambered for the FN 5.7x28mm cartridge used in guns like the FN P90 PDW, without needing a separate dedicated lower. The 8620 alloy bolt is the only moving part, sliding freely and removable for easy maintenance, and the aircraft-grade 7075-T6 receiver is rated well beyond typical operating pressures for long-term durability.

Panzer Arms has designed and manufactured rifles and shotguns for 48 years, beginning with hunting rifles in Turkey in the 1960s and now bringing modern firearms designs to the market.