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5.56 upper

The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO, fyv-FYV-six) is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, SS110, and SS111 cartridges. On 28 October 1980 under STANAG 4172 it was standardized as the second standard service rifle cartridge for NATO forces as well as many non-NATO countries. The 5.56×45mm NATO cartridge family was derived from and similar in dimensions to the .223, but is not totally identical to the .223 Remington cartridge designed by Remington Arms in the early 1960s.

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Recent contents
  1. Gunbuggy

    Stripped Aero Precision 20" 5.56 Upper Receiver W/ Pinned FSB

      1. For Sale
    • $250
    • Vancouver
    • Washington
    Up for sale is a fantastic condition Aero Precision 20" Upper Receiver. It has less than 300 rounds through it and looks great. The barrel is a 20" 5.56 NATO, Rifle Length, 1:7 Twist, 4150 Chrome Moly Vanadium, QPQ corrosion resistant finish, the same upper that they use on their M16a4 Special...
  2. S

    11.5 Sig MCX 5.56 Upper w/ AR Conversion Kit

      1. For Sale
    • $1200
    • Pullman
    • Washington
    For who might be interested, I have a brand new, never fired Sig MCX 11.5" 5.56 upper. Includes a conversion kit to run on a standard AR lower, giving you full MCX functionality without needing a dedicated MCX lower. I'm asking $1200 OBO. Not looking for any trades on this. Let me know if you...
  3. Duneblaster

    Stag Arms 10.5" 5.56 Upper w/a Midwest Industries Flash Can

      1. For Sale
    • $410
    • Roseburg
    • Oregon
    Stag Arms 10.5" 5.56 13.5" M-LOK Handguard Upper Features: HP and MPI Tested 10.5" QPQ 1:7 Aero barrel, 13.5" Stag Arms anti-rotation handguard (Aero), no forward assist receiver, Aero gas block & gas tube, with a Midwest Industries fluted flash can installed. Bcg and ch are not included...
  4. Knifejunkie

    11.5 m-lok 5.56 upper

      1. For Sale
    • $500
    • Longview
    • Washington
    11.5 m-lok 5.56 upper. Ballistic advantage barrel (I believe), BCM mcmr 10 handguard, black nitride gas tube, .750 gas block, nitride bcg, aero precision flip up irons, standard a2 birdcage, radian raptor LT charging handle, cerro forge upper. 200 rounds down range.
  5. Knifejunkie

    11.5 m-lok 5.56 upper

      1. For Sale
    • $500
    • Longview
    • Washington
    11.5 m-lok 5.56 upper. Ballistic advantage barrel (I believe), BCM mcmr 10 handguard, radian raptor LT charging handle, aero precision flip up irons, nitride BCG, standard a2 bird cage, black nitride gas tube, .750 gas block, cerro forge upper, 200 rounds down range.
  6. J

    Faxon arak 21 12.5 5.56 upper

      1. For Sale
    • $795
    • Coburg
    • Oregon
    Complete faxon piston upper. Installs on any ar lower. Adjustable piston and fast caliber swap to 300 blackout or 7.62. This is their newest version. Folding non reciprocating charging handle. Prefect with a side folding brace for a short package. $795 no trades. Will ship.
  7. Knifejunkie

    11.5" 5.56 upper mlok

      1. For Sale
    • $399
    • Longview
    • Washington
    11.5" 5.56 ballistic advantage (I believe), black nitride gas tube, .750 gas block, standard flashlight BCM mcmr-10 m lock handguard, cerro forge upper, aero precision flip up irons, radian raptor LT charging handle, nitride BCG. 200 rounds down range. $400
  8. Tack_Ryan

    Faxon 556 18" gunner upper.

      1. For Sale
    • $380
    • Lindale
    • Other
    For sale is a complete upper receiver group. Put together by the armorer at B King Firearms. Upper receiver is a thermal fit 7075 mod-0 upper with mod-0 handguard. Barrel is a Faxon 18" rifle length gas 4150 cmv nitrided 1/8 twist lightweight gunner profile barrel chambered in 5.56. Standard...
  9. DangoNoogen

    16" inch Radical Firearms AR-15 5.56 upper and MFT Battlelink Minimalist stock

      1. For Sale
      2. For Trade
    • $220
    • Portland
    • Oregon
    Upper and stock are in great condition with no damage/dings. Had for about a year and only shot around ~150 rounds out of it. Upper (no BCG/CH) and stock only, it's my current home defense backup so too lazy to take everything off until someone wants to buy it haha. Can sell separately, upper =...
  10. gfoster556

    Noveske 5.56 upper

      1. For Sale
    • $1000
    • Corvallis
    • Oregon
    Selling a like new 5.56 18" noveske complete upper. Has less than 100 rounds through it. Has a leupold mark ar 4-12x40 on it with Burris one piece mount. Asking $1000 for the upper and have a couple lowers I'd sell as well if interested.
  11. Tack_Ryan

    11.3" Complete BA Hanson Barreled 5.56 Upper with Brace

      1. For Sale
    • $550
    • Lindale
    • Other
    For sale is a custom built complete upper receiver from B King Firearms. Features a Ballistic Advantage Hanson 11.3 5.56 Barrel with pinned gas block, Breek Arms 3 prong flash hider with removable flash can, BKing Mod-0 thermal fit upper with free float mod-0 handguard, Breek Arms Sledgehammer...
  12. T

    NIB Aero M4E1T 10.5 5.56 Upper

      1. For Sale
    • $225
    • Albany
    • Oregon
    NIB Aero M4E1T 10.5" 5.56 Upper Bought for a project and decided to go a different direction. Does not include BCG or charging handle Brand new just been in my safe. New: $359.98 Asking &225 obo
  13. T

    NIB Aero M4E1T 10.5 5.56 Upper

      1. For Sale
    • $225
    • Albany
    • Oregon
    NIB Aero M4E1T 10.5" 5.56 Upper Bought for a project and decided to go a different direction. Brand new just been in my safe. New: $359.98 Asking &225 obo
  14. BrandoCommando

    AR 5.56 upper, no BCG

      1. For Sale
    • $400
    • Puyallup
    • Washington
    Combat Armory Billet upper Rise armament Dust cover and forward assist Ballistic Advantage 16" mid length 5.56 with pinned gas block, Barrel nut is torqued to 46in/lbs Black River Tactical custom gas tube AT3 15" Spear M lok handguard in Magpul OD Green Precision Armament EFAB muzzle device with...
  15. DameTime5

    Wilson Combat/Aero MK12 18 5.56 Upper with Surefire Warcomp $470

      1. For Sale
    • $470
    • Estacada
    • Oregon
    Bought from a buddy last week, decided to go a different route. Aero upper Midwest Industries 12.625” quadrail Wilson Combat 18” barrel with gas block and tube Surefire Warcomp CTN (Geissele takeoff, no SF mark) I’ll ship for $20 or face to face in Estacada/Sandy
  16. J

    11.5'' Sionics 5.56 Upper Receiver

      1. For Sale
    • $600
    • Eagle
    • Idaho
    Selling my lightly used 11.5" Sionics Upper. Willing to separate the parts at $475 for the stripped version or $600 with BCG and charging handle. Upper Receiver: 7075 M4 AR15 Style 5.56mm NATO Barrel: SIONICS 11.5" Medium Contour – 41V50, NATO Chamber, 1:7, 5R Rifling, Chrome Lined...
  17. Duneblaster

    Stag Arms 10.5" 4150V QPQ 5.56 1:7 Upper

      1. For Sale
    • $290
    • Roseburg
    • Oregon
    Unfired barrel, all parts are brand new. Complete, except for a gas block & muzzle device. This is new and has never had a gas block installed. 9" ATLAS R-One M-Lok handguard. The receiver was Thermo-Fit™ tightly to the Aero barrel. Never had a bolt carrier or charging handle installed. *Some...
  18. J

    Aero Precision 5.56 mid-length upper

      1. For Sale
      2. For Trade
    • $300
    • Coburg
    • Oregon
    Fired exactly 30 rounds threw this upper. No BCG. 100% factory built. $300 firm possible trade for 10.5 300 blackout upper. 541-999-2986 eugene oregon. Prefer face to face sale.
  19. dlh4x4

    BCM Kino 5.56 Upper *NEW*

      1. For Sale
    • $700
    • Lake Stevens
    • Washington
    New, unfired 12.5 BCM ‘Kino’ configuration upper. Includes BCM BCG and mil spec charging handle. Cash, Zelle or Venmo Shipping available for additional cost. https://bravocompanyusa.com/bcm-standard-12-5-carbine-upper-receiver-group-kino-configuration-kmr-alpha-9/
  20. H

    Budget 16 5.56 Upper new/unfired

      1. For Sale
      2. For Trade
    • $275
    • Sagle
    • Idaho
    New/unfired 16" upper in 5.56, includes ch/bcg, no FA. I can't remember where I bought this but it was part of a build kit I picked up a few years ago. Upper is factory built, the lower was the kit. $275 (+ shipping). No shipping to WA or anywhere else where prohibited. Willing to trade for...
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