CM15 5.56 AR15 Upper 16″ with Options

Chattahoochee Munitions manufactures the CM15 5.56 AR15 Upper, a complete 16-inch 5.56 NATO upper for any standard mil-spec AR15 lower. It has a billet 6061 upper receiver, a 15-inch M-LOK handguard with QD sockets, a CrMV 1:7 twist barrel threaded 1/2×28, a midlength gas system with a Superlative Arms adjustable gas block, and optional CM15 Low Mass bolt carrier group and ambidextrous charging handle, in your choice of Cerakote color.

A 16-Inch 5.56 AR15 Upper

The 5.56 AR15 Upper makes a full-velocity 5.56 NATO rifle on any standard AR15 lower with a stock, with no NFA paperwork for the barrel length. The midlength gas system softens the cycle compared with a carbine-length system.

The 15-inch M-LOK handguard runs nearly to the muzzle for a long support-hand reach and room for lights, slings and bipods. With a 1:7 twist, the 5.56 AR15 Upper stabilizes 55 gr training ammunition through 77 gr match and hunting bullets.

5.56 AR15 Upper Specifications

• Chambering: 5.56 NATO (also fires .223 Remington)
• Barrel: 16-inch CrMV, QPQ nitride, 1:7 twist, .750 gas journal, 1/2×28 thread
• Gas system: Midlength, Melonite gas tube, Superlative Arms adjustable gas block
• Upper receiver: CM15 billet 6061 aluminum with lightening reliefs and a milled Picatinny rail channel
• Handguard: CM15 15-inch 6061 M-LOK, QD sockets at 3 and 9 o’clock, full Picatinny top rail; B5 Systems rail covers in Black or Coyote
• Bolt carrier group and charging handle (optional): CM15 Low Mass BCG with 9310 hardened steel bolt, 17-4 stainless firing pin, 8620 carrier and key, MPI tested, S7 extractor; CM15 Warhammer ambidextrous charging handle made in collaboration with Breek Arms
• Color: Black Tungsten, Black, Cobalt Kinetics Green, FDE Metallic, FDE, Sniper Grey, OD Green or Burnt Bronze Cerakote, or another single color noted at checkout
• Muzzle: optional muzzle device selection or a thread protector
• Fits: standard mil-spec AR15 lower receivers

5.56 NATO and .223 Remington Ammunition

This CM15 has a 5.56 NATO chamber and fires both 5.56 and .223 Remington; never fire 5.56 in a barrel marked only .223. For a complete trigger group, the CM15 firearms use a TriggerTech Duty trigger. Read 5.56 vs 223, 5.56 barrel length and 5.56 twist rate.

Suppressor

For a gas-operated AR15 firing supersonic 5.56, Chattahoochee Munitions recommends a flow-through suppressor, which limits back pressure. See 5.56 suppressor.

Other 5.56 Uppers and Complete Firearms

Other CM15 5.56 uppers: 5.56 Pistol Upper, 5.56 NATO Upper. Complete firearms: 5.56 NATO Rifle, 5.56 SBR, 5.56 PDW. Browse the CM15 5.56 Uppers category and the full lineup at Garrison 5.56.

5.56 AR15 Upper FAQ

Who makes the CM15 5.56 AR15 Upper?

Chattahoochee Munitions manufactures the CM15 5.56 AR15 Upper as a complete 16-inch 5.56 NATO upper.

Does the 16-inch 5.56 AR15 upper need NFA paperwork?

Not for the barrel length. 16 inches is a rifle under federal law.

What gas system does the 5.56 AR15 upper use?

Midlength, with a Superlative Arms adjustable gas block.

Does the upper include a bolt carrier group?

Optional. Select the CM15 Low Mass bolt carrier group and ambidextrous charging handle at checkout.

What twist rate is the barrel?

1:7, for 55 to 77 gr bullets.

Can this CM15 shoot .223 Remington?

Yes. The 5.56 NATO chamber fires .223 Remington safely.

What colors are available?

Black Tungsten, Black, Cobalt Kinetics Green, FDE Metallic, FDE, Sniper Grey, OD Green or Burnt Bronze Cerakote, or another single color noted at checkout.

What thread pitch is the barrel?

1/2×28.

Is 556 the same as 5.56 NATO?

Yes. 556 is shorthand for 5.56 NATO.