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BKF M4 MOD-0 12.5″ 5.56 Govt Profile Carbine Length 4150 CMV 1/7 Twist Barrel W/ FSB (No Handguard)

(7 customer reviews)


Available on backorder



This product is 100% Made in the USA! Our gas tubes, gas blocks and even roll pins are all proudly manufactured in the US. All Complete uppers are headspaced prior to shipping and test fired.


  • BKF Dry Film Lubed Assembled Upper Receiver w/ T-Marks
  • BKF AR15 12.5″ 5.56 Govt Profile Carbine Length 4150 CMV 1/7 Twist Nitride Barrel W/ FSB, Handguard Cap and Delta Ring Assembly
  • Carbine Length Gas Tube Nitride
  • BKF A2 Flash Hider
  • Product comes assembled
  • No Handguard, BCG or Charging Handle

Standard Upper Features:

  • M4 Feedramps
  • .250 takedown pin holes
  • Laser engraved T-marks
  • Upper is Assembled

This BKF 5.56 chambered 12.5 inch Government Profile Barrel is machined from 4150 Chrome Moly Vanadium steel with a QPQ Corrosion Resistant Finish and QPQ coated M4 feed ramp extension. This barrel includes the front sight base (F-Marked) , handguard cap and delta ring assembly.

All NFA/ATF Rules Apply
You may use this barrel with a lower receiver that is a Registered SBR, Machine Gun, or Pistol. Possession of this barrel along with a Non-NFA lower receiver is Prohibited, except when permanently attaching a muzzle device extending the length to 16 inches.

Additional Info

Length 12.5″
Material 4150 Chrome Moly Vanadium
Profile Government
Finish QPQ Corrosion Resistant
Gas System Length Carbine
Gas Block Journal .750″
Twist Rate 1:7 inches
Muzzle 1/2×28 Threaded
Weight 30oz w/ FSB

B. Kings Firearms barrels are manufactured by a Top Tier Barrel Manufacturer to our specifications. B. Kings Firearms barrels are made for combat and heavy duty use. We rate all of our Pinned Gas Block models for full auto use. We guarantee 1 MOA or better on all BKF barrels when used with match grade ammunition.

Additional information

Weight 2 lbs
Dimensions 20 × 2 × 2 in

7 reviews for BKF M4 MOD-0 12.5″ 5.56 Govt Profile Carbine Length 4150 CMV 1/7 Twist Barrel W/ FSB (No Handguard)

  1. Anonymous (verified owner)

    Well built .. very accurate ..mated to a unmarked Anderson lower with no play… the barrel length is just about perfect … Fitted it with a 2a t3 muzzle device almost no flash for a shorter barreled upper … Not like a 10.5 and or 11.5 both of which display a much greater flash signature by far …. Well balance in the hand… barrel is quality and the company logo is in a good place and I think is a very nice touch … Over all quality fit and finish are nice

  2. Jacob (verified owner)

    I haven’t put any rounds through the upper yet, but Inspection of the upper I found zero issues. I plan on buying from this company due to availability of items, their hard to beat prices, and their quickness in getting items shipped to you. To the owner of this company I wanna say thank you from one vet to another vet, and you now have a customer for life.

  3. Gary Adkins (verified owner)

    Very well put together, better than others I have bought elsewhere, super fast shipping was a definite plus, I will be buying from you guys again, thank you–Semper Fi!

  4. Aaron (verified owner)

    FSB installed straight, no cant. Good barrel, headspace checks out.

  5. Anonymous (verified owner)

    Shipped quickly and arrived as described. Thanks.

  6. Jeremy W. (verified owner)

    Nice upper. Perfect for your SBR or pistol AR project. I’m using mine with a custom barrel collar to mount an Allen Engineering AEM5 suppressor.

  7. Aaron Johnston (verified owner)

    Well put together, no cant in FSP. Fitted with customer collar for AEM5, took it out to 425yds with a red dot and consistent hit on deer size steel.

  8. Robert S. (verified owner)

    Excellent product. Very nice upper. seems to be well made everything is tight and right.

  9. Gilles M. (verified owner)


  10. frankarey3 (verified owner)

    Great product and price. I’ve owned this upper for (2) years now and with hundreds of round ran through it, its still working great. These guys now how to build an AR upper. Quality is there which is rare these days. Keep it up gentlemen!

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