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BKF M4 Carbine Buffer Tube Assembly – Mil Spec

(119 customer reviews)


644 in stock


All components are quality Mil-Spec parts for completing your AR15 lower receiver.


  • BKF T6 6061 U-cut Anti-Rotation Mil-Spec buffer tube (6 Position)
  • BKF 3 oz carbine buffer
  • BKF Carbine buffer spring
  • BKF Steel end plate
  • BKF Steel castle nut

Additional information

Weight .5 lbs
Dimensions 10 × 2 × 2 in

119 reviews for BKF M4 Carbine Buffer Tube Assembly – Mil Spec

  1. Paul Erickson

    Quality parts by Aero. Another flawless transaction with bkingsfirearms

  2. James Heagy (verified owner)

    My order shipped very fast and was packaged well. The product works great. I will use BKF in the future. Thanks.

  3. Erik Sutherly (verified owner)

    Great product

  4. Richard (verified owner)

    Good quality and a great price

  5. Dustin (verified owner)

    Great quality buffer kit, all Aero Precision parts, bought two of these on sale to finish off a couple lowers and they went together perfectly. Would buy again. B Kings is also my new go to for AR builds. Great prices, great shipping times, and veteran owned.

  6. John England (verified owner)

    Good product at a super price.

  7. Chris Kwiatkowski (verified owner)


  8. Keaton (verified owner)

    Awesome product

  9. Matthew M. (verified owner)

    Is it Aero or is it BKF? I can’t tell the difference…….

  10. Andrew (verified owner)

    Have not installed yet but seems nice.

  11. Dustin (verified owner)

    An excellent and inexpensive kit for a build or spare parts.

  12. Joseph G. (verified owner)

    Fit finish and function were perfect! Keep up the good work guys!

  13. Robert Galperson (verified owner)

    Great Price, great quality, fast shipping, great customer service!

  14. Todd R. (verified owner)

    Good solid basic parts at a great price. Will definitely use this vendor again.

  15. Dennis (verified owner)

    Fast shipping and product as described

  16. Anonymous (verified owner)

    Excellent assembly combo at a great price. Fast shipping and great service, too.

  17. Dallas (verified owner)

    I love your company and the way you do business. Will definitely use you in the future

  18. John E. (verified owner)

    Good quality kit for the money.

  19. Travis (verified owner)

    Exactly as advertised

  20. Joshua (verified owner)

    Fit and finish are excellent, shipped super fast.

  21. Michael T. (verified owner)

    Great Parts! No Problems, will buy again for my next Build!

  22. Anonymous (verified owner)

    Great quality. The tube has a nice finish that matches me aero receivers perfectly

  23. Lane T. (verified owner)

    Great buffer assembly, love the light weight.

  24. Anonymous (verified owner)

  25. christopher (verified owner)

    Good to go

  26. Mason M. (verified owner)


  27. Clay D. (verified owner)

    Best price around, most others charged the same or more for just the buffer tube alone. Shipping very reasonable unlike most places these days, and shipped fast. Thank you

  28. sean (verified owner)

    Does what it says on the box. At time of purchase it was the best price online for a 6061 tube complete kit.

  29. brad c. (verified owner)

  30. Anonymous (verified owner)

  31. mad_mongolian7734 (verified owner)

    Quality and affordable. Would happily buy again for next carbine build.

  32. Michael B. (verified owner)

    Came fast, and fit perfectly, great product

  33. Alex S. (verified owner)

  34. Thomas M. (verified owner)

    Top quality, fast shipping will buy from again!

  35. Joshua Provost (verified owner)

    I got several of these when they first came out and they were nice and cheap for what you got. The only real downfall they have is the retainer for the detent is the style that is supposed to go around the sides of the detent but if you screw it in far enough to do that the upper won’t go on because the top of the buffer tube sticks through the lower. So you’re stuck with just 2 very small contact points on the edges of the detent or shaving metal off your new buffer tube. I’m not in the military or a police officer so it’s not a huge concern to me as the rifles they went on will be primarily for range shooting.

  36. Joshua Meyer (verified owner)

  37. Derrick M. (verified owner)

    Works just like it should

  38. Andrew D. (verified owner)

  39. Thomas (verified owner)

  40. Jon G. (verified owner)

    Just what I wanted. Can’t beat the price.

  41. Tyler H. (verified owner)

  42. Mike P. (verified owner)

  43. Barry M. (verified owner)

  44. Kirklyn (verified owner)

    Got here on time looks perfect thank you!

  45. Bradley Hunt (verified owner)

    Great kit, great price, flawless operation.

  46. Anonymous (verified owner)

  47. Robert Weber (verified owner)

  48. Robert C. (verified owner)

    Outstanding service and quality

  49. Anonymous (verified owner)

    Functions flawlessly, threads are tight felt confident when I cranked it down with a wrench it wasn’t going anywhere.

  50. durand henderson (verified owner)

    Well packaged. Fit perfect. Excellent pricing.

  51. Timothy Brady (verified owner)

    Excellent service!!!!

  52. Mark R. (verified owner)

    Good quality parts at less money than the competition, and he doesn’t take 6 weeks to ship. Plus he’s a bet? No brainer for me.

  53. Daryl Lacourse (verified owner)

  54. Sharon A. (verified owner)

    Excellent quality and finish.

  55. Sean P. (verified owner)

  56. Keith B. (verified owner)

    Good parts fast service

  57. Patrick N. (verified owner)

    When everything is sold out everywhere I came to B King for the parts I needed, not only were they in stock but the prices were not inflated, great product good price & fast shipping.

  58. Paul (verified owner)

    100% as advertised

  59. William M. (verified owner)

    Great Product at an affordable price!

  60. Steven (verified owner)

    Came in a timely fashion.

  61. Ronald K. (verified owner)

    Product EXACTLY as described.
    As always from B. King prompt shipping at reasonable prices for quality products. B. King’s service actually makes working on my own weapons enjoyable since the parts I order are so prompt.

  62. Anonymous (verified owner)

    I will always order here. Shipping is fast and the price is just right. Keep it up!

  63. James (verified owner)

    Product was as advertised and was delivered promptly.

  64. George D. (verified owner)

    The buffer itself was high quality. The buffer tube is a nice matte color. Really good kit overall.

  65. Keith O. (verified owner)

    Everything looks to be well made. The main reasons I selected this buffer tube were because of the price on the whole assembly, and the fact that the tube had the forward flange which extends over the buffer retainer. I have had a retainer come out in the past and put an end to a shot string as it lodged in the fire control group. The spring being coated is a bit of a negative, but that’s my personal preference.

  66. John Turner (verified owner)

  67. Brian Richards (verified owner)

  68. John Golden (verified owner)

  69. Jack Watts (verified owner)

    Really like shopping with you all always good prices and prompt shipping, Thanks until I visit again

  70. Anonymous (verified owner)

    Great product

  71. Joe kennedy (verified owner)

    It was great! Perfect fit and great service. Will be back for more.

  72. david c. (verified owner)

    The AR15 buffer assembly was easy to install and the gun ran perfectly

  73. gerald yabeny (verified owner)

    Excellent price and quality

  74. Anonymous (verified owner)

  75. Mike S. (verified owner)

    Great price fast shipping product worked perfect

  76. Jeffrey MIller (verified owner)

    Product is exactly as expected. The USPS sucks. Way to long to get the merchandise(not your fault). Thank you.

  77. William A. (verified owner)

    Bare bones, no frills kit that just works for a great price. Fast shipping with all things considered during this crazy times. Glad I found this company, as I will be a repeat customer.

  78. Randall (verified owner)

    part quality was as expected, shipping was slow

  79. Eric Kisch (verified owner)

  80. Dustin C. (verified owner)

  81. Bradley (verified owner)

    Great product, great price, fast shipping

  82. GUY LETOURNEAU (verified owner)


  83. Anonymous (verified owner)

    Very nice, thank you

  84. Jason (verified owner)

    Cut out for detent was a little shallow making it difficult to complete final turn of buffer tube into place over detent. But i got it done.

  85. Peter (verified owner)

  86. Fred Schneider (verified owner)

  87. Kenneth A. (verified owner)

    Great quality and fast service

  88. Josh T. (verified owner)

    Great service… Funny thing is I didn’t realise where B kings was located. I’m in MN. I was born and raised in Lima OH. Small world!

  89. Wesley Pinkston (verified owner)

  90. Rich L. (verified owner)

    In stock and good quick service thanks!

  91. Michael J. (verified owner)

  92. mark.a.horsley (verified owner)

    Used buffer tubes on PSA lower receiver builds. Fit and functioned perfectly. Excellent quality.

  93. Anthony (verified owner)

    Nice quality

  94. Anonymous (verified owner)

  95. JOHN B. (verified owner)

    Great part great for great price

  96. CLAYTON (verified owner)

  97. Nicholas (verified owner)

    great product, awesome price, fast shipping

  98. Roger Ramey (verified owner)

    Excellent parts for the AR 15 carbine. Everything fit perfectly. The shipping was very fast.Great to do business with.

  99. Andy S. (verified owner)

  100. Anonymous (verified owner)

    Excellent quality,excellent price!

  101. Don H. (verified owner)

    Fast shipping, great price, excellent product!

  102. Daniel S. (verified owner)

    Great price and everything works properly. That said, if I remember correctly, there was something a little different about the buffer retainer cutout. Typically, I over thread the extension slightly, insert and capture the take down detent pin and spring. Then I rotate the extension back to the correct position and slip the end plate down. There was something about the cutout that prohibited that method. Not the end of the world just a bit of a PITA getting the detent spring properly captured without kinking it.

  103. Anonymous (verified owner)

    Best prices, extremely fast shipping. Thanks again

  104. jaime c. (verified owner)

    Great product, and great shipping.

  105. Benjamin B. (verified owner)

    Product as described. Went together no problem. Fast shipping. Great company! Will order from them again in the future!

  106. paul friend (verified owner)


  107. Andrew N. (verified owner)

  108. Robert wylie (verified owner)

  109. Chris V. (verified owner)

    I built three lowers using these kits, two pistols and one rifle, all chambered in 7.62×39, the shipping was fast, I would recommend this assembly for anyone looking to build.

  110. Peter M. (verified owner)

  111. Dan Wilder (verified owner)

  112. Brian P. (verified owner)

  113. Philip Truman (verified owner)

    Everything is working properly great place for accessories!

  114. kenneth (verified owner)

  115. robert t. (verified owner)

  116. Barry M. (verified owner)

  117. Brian B. (verified owner)

    exactly what I needed at a great price

  118. Rick T Errhalt (verified owner)

    The first product that I ordered was not the correct product at all, and was damaged on top of that. Reached out to the company for a replacement, but am still waiting on said replacement to ship as of the writing of this review. For the amount of wasted time with this company I would have rather spent $10 more dollars somewhere else. Even had to pay to get packaging to send the original product back.

  119. Paul F. (verified owner)

    Very positive and quick delivery

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