5.56 NATO & .223 Wylde AR-15 Upper Assemblies

5.56 NATO & .223 Wylde AR-15 Uppers by Barrel Length

Shop 5.56 NATO and .223 Wylde AR-15 uppers from Moriarti in a wide range of barrel lengths, handguards and finishes. Browse everything from micro ARP and AR pistol uppers to 16-inch carbine and long-barrel rifle configurations. Choose from 5.56 NATO and .223 Wylde chamberings for recreational, target and general-purpose AR-15 applications. Compare each upper for exact barrel length, twist rate, gas system, rail and included components.

What is the difference between a 5.56 NATO upper and a .223 Wylde upper?

A 5.56 NATO upper uses a 5.56 NATO chamber, while a .223 Wylde upper uses a hybrid chamber designed to safely accommodate both 5.56 NATO and .223 Remington ammunition while incorporating chamber geometry intended to support accuracy with .223 ammunition. Always follow the ammunition and specifications listed for the individual barrel.

How to Choose a 5.56 / .223 Wylde Upper

• 5" – 8.5" (Micro ARP and pistol uppers): the most compact setups for AR pistols and SBR builds; expect more blast and flash, so a shroud or brake helps.
• 10.5" – 12.5": a popular balance of handling and velocity for pistol and SBR builds, usually with carbine-length gas.
• 16": the standard rifle length with no NFA paperwork; carbine or mid-length gas, 1:7 or 1:8 twist.
• 18" – 24": rifle-length gas and heavier or bull barrels for precision, varmint and long-range work, often in .223 Wylde.

FAQ

Will these uppers fit my AR-15 lower?

Yes. Every upper here fits a standard mil-spec AR-15 lower receiver and uses a standard 5.56 bolt carrier group and STANAG/AR-15 magazines.

Can a 5.56 or .223 Wylde upper shoot .223 Remington?

Yes. Both chambers safely fire 5.56 NATO and .223 Remington. The .223 Wylde chamber adds a tighter throat for better accuracy with .223 loads.

Which twist rate should I choose?

1:7 and 1:8 handle the widest range, from 55 gr to heavy 77 gr bullets. 1:9 is best for 55 gr to 69 gr. Very short Micro ARP barrels often use a fast 1:5 twist.

Is a bolt carrier group included?

It depends on the listing. Most uppers ship without a BCG; the ones that include it say so in the title or description.

Related: all AR-15 upper assemblies · 5.56 Micro ARP · 5.56 build kits · 300 Blackout uppers