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BCM MK2 Buffer System

This product is regulated by ITAR. It can only be shipped in the USA.

What’s Included | Buffer Selection | Specs | Pictures | Restrictions

The BCM MK2 Buffer System is a significant improvement over your run-of-the-mill carbine system. The MK2 features a longer receiver extension and a longer buffer while utilizing a standard rifle-length action spring. But why does all that matter?

It all starts at the longer 8-position receiver extension. This allows the use of a longer rifle-length action spring, which more evenly spreads the load over more coils and lets the system use more weight for the same amount of input, effectively widening the operating range of the entire system and making the rifle less sensitive to ammo choice, cleaning (or lack thereof), and environmental conditions.

A longer buffer is used to compensate for the longer receiver extension; this provides room for an extra buffer weight, bringing the total up to four weights instead of the standard three found in a carbine buffer. This gives more adjustability, with BCM’s buffer weights ranging from 3.8oz (T0) to 7.4oz (T4). More weight not only slows the cycle of the gun and reduces recoil impulse, but it also delivers more chambering force and helps resist bolt bounce. The MK2 buffer also features an internal biasing spring, which ensures that the weights always sit towards the front face of the buffer, reducing noise and providing consistent carrier speed, aiding in more reliable chambering and extraction.

The BCM MK2 is a semi-proprietary buffer system. It is not compatible with Mil-Spec Carbine buffers or Mil-Spec Carbine action springs.


  • BCM MK2 Buffer T1 or T2
  • BCM MK2 Receiver Extension
  • BCM Rifle Length Action Spring
  • BCM QD Endplate
  • BCM Castle Nut

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5.56 RiflesUnsuppressed 50% Suppressed/Unsuppressed
or Low Back Pressure Suppressor
Suppressed only
BCM MK2 16″ MidLength GasT1T2T2
BCM MK2 11.5″ Carbine GasT2T2T3
18-20″ Rifle GasT1T2T2
13.9-16″ MidLength GasT1T2T2
14.5-16″ Carbine GasT2T3T3
11.5-12.5″ Carbine GasT2 T2 T3
10.3/10.5″ Carbine GasT2T2T3

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  • Lessens felt recoil without compromising reliability
  • Provides more consistent carrier velocity, which aids in reliability over conventional carbine buffer systems
  • Increased internal counterweight travel reduces bolt bounce
  • Internal spring to reduce the noise of the counterweight shifting and ensure more consistent weight placement
  • Mil-Spec M16A4 rifle spring with more spring coils than M4 carbine increases consistency and widens the operating envelope of your rifle
  • Buffer made of 7075-T6 aluminum, hard coat anodized for lasting endurance; comprised of Mil-Spec components
  • BCM US Patent #10415907

Made in the USA.


Action SpringM16A4 (Rifle Length)
BufferProprietary MK2 Buffer (VLTOR A5 Compatible)
Buffer WeightT1: 4.7oz T2: 5.6oz
Receiver ExtensionBCM MK2 – 8 Position
Castle Nut BCM Mil-Spec
End plate BCM QD

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This product is restricted by International Traffic in Arms Regulations (ITAR) and cannot be shipped outside of the US.

This product cannot ship to Washington State due to unconstitutional restrictions. Because we believe that all citizens should have the same rights, we will not make any exceptions for military, law enforcement, or government personnel.

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