BCM® MK2 Receiver Extension

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Our BCM MK2 Receiver Extension for your AR15, M16, M4. Machined from 7075T6 and manufactured to Mil-Spec dimensions and specifications. Mil-Spec receiver extensions have a slightly smaller dimension where the stock slides on.

Hard Coat Anodized per Mil-A-8625F, Type III, Class 2

These tubes should be used with stocks such as USGI, BCMGUNFIGHTER™, Colt, LMT, SOPMOD, VLTOR, Stag Arms, and others that a made to the Mil-Spec size.

*NOTE* These buffer tubes require a rifle action spring and specific BCM MK2 buffer, carbine and rifle buffers will NOT work.
***This product contains chemicals/materials known to the State of California to cause cancer and other reproductive harm. To learn more, visit www.p65warnings.ca.gov.***

92 Reviews

  • 5
    Best A5 Buffer

    I've used three buffer tubes that can be used with the A5, and BCM is by far the best fit and finish. Has the dry lube spray on the inside. Smooth, dark black finish, which handles some "banging around" without showing any damage.

  • 5
    The best fit

    I love the this tube. Especially the fact that I can completely collapse my brace or stock when I need to unlike some other tubes.

  • 5

    works great with A5 buffer weight and springco

  • 5

    Works well. Prefer this one over vltors

  • 5
    A5 RE

    As is with every other BCM product, this one was also top notch! And speaking of notches, this buffer tube (or receiver extension, whichever you prefer to call it) has 8 adjustable positions for the stock. BCM always has my highest recommendation for parts!

  • 5
    BCM A5 option

    I was sad to find I couldn't track down an A5 tube for my next build. Then I found out BCM made one, being a fan of BCM and their products I picked it up.
    It:s fit and finish is top notch as always, and it has performed well for me so far.

  • 5
    Buffer tube

    solid form, fit n finish, BCM is beyond reproach love everything they make

  • 5
    A5 intermediate

    If you’ve used the A5 system you already know how great it is, especially for shorter barrels. Fit and finish were great, BCM QC is top notch.

  • 5

    Much better alternative to the VLTOR tube. Allows longer stocks to fully collapse and lock into place, and even looks better! Paired this with a VLTOR A5H2 kit and it is perfection on all of my uppers.