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BKF M4 MOD-1 Fluted 8-Position Lower Build Kit W/ Combat Control Kit in Nitride (BKF Sopmod)

(5 customer reviews)


12 in stock


This Combat Control Kit is made from billet 4140 heat treated alloy steel with a beautiful nitride finish. The textured surface gives it an enhanced gripping ability. The ambidextrous safety selector can be used as a 90° or 60° throw lever. The mag release is deeply threaded to allow for normal height installation, or thread it halfway to get an extended mag release! The oversized bolt catch makes those mag reloads much easier and quicker. A must have for every build!

BKF MOD-1 AR15 Fluted 8 Position Anti-Tilt Carbine Length Buffer Tube Assembly Features include:

  • Billet machined from 6061-T651 aluminum for tighter concentricity than a forging or impact extrusion to reduce potential for bolt carrier binding.
  • 8 position adjustment with machined indicators visible through any stock with a viewing port located at the stock latch pin. Extended positions, increment adjustments have a finer spaced length of pull.
  • Mil Spec extension diameter of 1.148, and thread diameter of 1.185
  • Carbine length
  • Extended carrier support flange that supports the carrier for better anti-tilt performance.
  • Self aligns with the buffer detent.
  • Fluted for a more aesthetic look
  • Chamfered edges on the stock guide ramps for better feel
  • 3 Drain holes at 6 O’clock
  • Weight 3.45 oz
  • Proudly made in the USA!!!


  • BKF Sopmod Carbine stock
  • BKF MOD-1 AR15 Fluted 8 Position Anti-Tilt Carbine Length Buffer Tube
  • BKF Standard Carbine buffer W/ Steel Weights (3). (3.0oz)
  • BKF Carbine Buffer spring
  • Steel Mil Spec end plate and Mil Spec locking (castle) nut – Phosphate Coating
  • BKF Fire Control Group (Trigger, Hammer, Disconnector) – Phosphate
  • Trigger Pin – Nitride
  • Hammer Pin – Nitride
  • Hammer Spring
  • Trigger Spring
  • Disconnector Spring
  • Takedown Pin – Nitride
  • Pivot Pin – Nitride
  • CAS – Combat Ambi Selector 60/90 – Nitride
  • CMR – Combat Mag Release – Nitride
  • CBC – Combat Bolt Catch – Nitride
  • Mil-Spec Mag Catch Latch – Nitride
  • Mil-Spec spring kit
    • Pivot Pin Spring
    • Takedown Pin Spring
    • Buffer Retainer Spring
    • Selector Spring
    • Bolt Catch Spring
    • Magazine Catch Spring
  • Mil-Spec Small Parts Kit
    • Takedown Pin Detent
    • Pivot Pin Detent
    • Selector Pin
    • Bolt Catch Roll Pin
    • Bolt Catch Plunger
    • Buffer Retainer

This lower parts kit does not include the pistol grip or trigger guard.

Additional information

Weight 1.5 lbs
Dimensions 10 × 8 × 4 in

5 reviews for BKF M4 MOD-1 Fluted 8-Position Lower Build Kit W/ Combat Control Kit in Nitride (BKF Sopmod)

  1. Darren (verified owner)

    Everything went great.

  2. Brian J. (verified owner)

    Outstanding quality ad a just a great comprehensive kit. The stock is a very tight fit on the buffer tube. Really impressed with the lock up and the over all quality.

  3. Paul Fox (verified owner)

    Great value. The stock is awesome, and the lpk is of good quality. All the controls feel good, selector is crisp, etc.

  4. Brian G. (verified owner)

    Fit and function of this parts kit is excellent. It was shipped super fast. Very happy with every purchase I’ve made from BKF. Thank you for great customer service.

  5. Roel (verified owner)

    Very nice products from B. Kings, fast shipping. This is the third time i have bought from them and they always deliver very well made items, great customer service as well. I will be buying from them again. Thanks and keep it up.

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