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Kratos Design Group 8-Position Receiver Extension | A5 Compatible


(11 customer reviews)

Weight: 4.3oz
Material: Impact-Extruded 7075 aluminum
Finish: Type III, Class 2 Hardcoat Anodize
Made in USA


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Frequently Bought Together

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Price for all three: $121.85

The Kratos Design Group 8-Position Receiver Extension is fully compatible with VLTOR’s patented A5 system. This receiver extension is slightly longer than the traditional M4 receiver extension to utilize rifle length springs and A5 buffers and is designed to work with Mil-Spec dimensioned M4/AR-15 type collapsible stocks.  For AR15/M16 applications, it must use Vltor A5 or A5 compatible buffers & rifle length recoil springs We reccomend the Sprinco Green Spring for most applications.

This receiver extension tube can also can be utilized as a replacement receiver extension for the AR-10 rifle.

Dialing in the perfect length of pull is easy with eight adjustable stock positions.

The Kratos Design Group buffer tube is made of impact-extruded 7075 Aluminum and is made to withstand rigorous use. The finish is a Type III Class 2 hardcoat anodize. 

Weight: 4.3oz
Material: Impact-Extruded 7075 aluminum
Finish: Type III, Class 2 hardcoat Anodize
UN-2A threads
Made in USA


Additional information

Weight 2 oz
Dimensions 6 × 2 × 1 in

Black Anodized, FDE/Tan Anodized (Shade 2), ODG Anodized, FDE/Tan Anodized (Shade 1)

11 reviews for Kratos Design Group 8-Position Receiver Extension | A5 Compatible

  1. Charles Walker (verified owner)

    The Kratos A5 RE is everything you’d expect a well put together Receiver Extension to be. It’s easily on par with other high end RE’s like the FCD RE5F. Definitely a worth while alternative that I’d have no reservations putting on any of my rifles. Fit well with Hodge Mod 2, FCD ESF-H, RBF, CNF, and Vltor EMOD stock. Fit and finish were great. RE came in the coolest container (like plastic drill big containers) for protection. Great job Kratos Design Group.

  2. David Bushelman (verified owner)

    To start the finish of this extension is top notch. There are very minimal extrusion marks with a uniform anodizing. This is not an easy task. Function is also top of the line. The threads tightly engaged a hodge, fn, centurion and even a palmetto state lower. Multiple end plates and castle nuts were fitted with zero complaints. I will definitely use this product in future builds.

  3. adamstone026 (verified owner)

    Physically, the Kratos 8 position buffer tube is absolutely solid with the quality you’d expect. I found it to be on par with other similar buffer tubes like the BCM MK2 and VLTOR A5. It threaded onto and interfaced with both a BCM and LWRC lower receiver without any issues.

    Testing yielded great results as well. I tested two different buffers in conjunction with a Sprinco green spring in this tube and the performance was great with both. The buffers used were a VLTOR A5 and BCM MK2 buffer. Overall, I have no complaints and zero issues and this is a totally viable alternative to other popular buffer tubes.

  4. Gregory Williams (verified owner)

    The threads are the absolute stand out feature. Thread depth is perfect, no burrs to be found, and it was the cleanest feeling install I’ve experienced. Overall fit and finish is superb, and going with 8 positions is a perfect choice. Inside the tube is nice and smooth as well which is always nice to see, as I’ve seen one or 2 others that we’re textured as hell inside. The tube was installed on rifle with a 14.7 barrel with midlength gas, and was filled with a sprinco spring and vltor A5H2 buffer. The rifle was shot suppressed with an RC2. Rifle cycled flawlessly.

  5. Spencer Dereich (verified owner)

    If your looking for a high end buffer tube this is it. The finish is great. The Anodizing is very thick. The inside of the tube is one of the smoothest I’ve ever felt. Threads are nice and tight. Used it on a Geissele lower and mated up perfect. I’d definitely use this buffer tube again.

  6. Paul Schoelich (verified owner)

    This tube was provided to me by Kratos, but that in no way affects this review.

    I compared it to a vltor tube and an fcd tube I have here. I’m no machinist, but dimensionally with a caliper, it’s in line with those two. The threads as far as I can tell are in spec, as I threaded it into an aero, geissele, lmt and old production mega billet receivers I have here. Also used fcd, pws, and a few no name castle nuts. It threaded fine and I didnt distinguish any different feel or play vs the other tubes. The finish is on par with the others as well. It may have been luck of the draw, but this is the best looking extrusion of the bunch. Several stocks, b5, magpul moe slk and ctr, sba3 brace, fit perfectly as well.

    When assembled, the action feels as smooth as the other tubes with the same buffer and spring(vltor A0 and geissele super 42 rifle length spring).

    Overall I’m impressed with this part, the rifle ran as it did with the vltor tube on it. A great option for your next build!!!

  7. mewhitten2 (verified owner)

    This isn’t a cheesy, thin, wannabe A5 tube. This is quite possibly the best engineered buffer tube on the market today because it goes well above and beyond “Mil-spec” minimums. I attached this buffer onto a traditionally gassy, 14.5″ LMT DI upper and MARS lower with a VLTOR A5H2 buffer and Springco Green spring. Then I tested with high pressure rounds (M855A1, MK262, and some standard m193). Every single round ejected consistently to the same spot at the 3 o’clock position with 0 failures in 100 rounds.
    No unusual wear to any components, no issues what so ever. Next up is testing with a suppressor on.
    Morgan Freeman voice on / The truth is, this is the best damn A5 buffer tube on the market, and I have no doubt you will agree.

  8. Kristopher Swift (verified owner)

    It is exactly as God intended an A5 receiver extension to be. The threads are perfect, silky and smooth and the finish is perfect. One thing I noticed is that my stock seemed to be less wobbly, which is always a good thing. I have 4 other A5 extensions currently in use and I haven’t had any issues with them at all, They are from a brand most commonly referred to by three letters. I’m not going to tell you the Kratos Design Group extension is the best extension I have ever used, but it seemed to be more satisfying to assemble than the other 4 I have. I am going to order another one for my next “build”.

  9. Justin Bogue (verified owner)

    Amazing reciver extension. Fit and finish is amazing Attention to detail is top notch . This is my second one first being a carbine length black, and I will keep coming back for more ! Keep it up guys!!

  10. (verified owner)

    Tip to tail this A5 buffer tube checks all the boxes. Compatible with Vltor and BCM components. Fit and finish exceed my expectations.

  11. Jeff Chaiet (verified owner)

    Quite possibly the best buffer tube I’ve ever used. You can honestly feel the quality while holding it. Fit and finish was flawless. Inside surface is smooth with no burrs or machining marks. Threads are beefy and machined well. Threaded into two different brands of lowers (Centurion, FCD) with no issues. Zero play even before tightening castle nut. Three different brands of stock (Magpul, VLTOR, B5) slid on easily, but were snug and had zero play or rattle. The 8 position design is excellent for fine tuning length. VLTOR and BCM MK2 buffers fit perfectly. Completed build performed perfectly.

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