Armaspec Sound Mitigation Buffer (SMB) Gen3

Hrachya H
by Hrachya H
Armaspec SMB Gen3, H2

Armaspec have recently released the third generation of their Sound Mitigation Buffer or SMB. This AR-15/AR-10 buffer assembly has a captured recoil spring that does not contact the internal surface of the buffer tube thus resulting in smoother and quieter operation of the action. Let’s take a closer look.

Armaspec @ TFB:

Armaspec SMB Gen3, H3

Armaspec Sound Mitigation Buffer Gen3 is a drop-in part that simply replaces the standard AR-15/AR-10 recoil spring and buffer without any modifications to the weapon. The spring weight can be adjusted by cutting the spring with about .25 lbs per coil of tension reduction. The company does not recommend trimming more than 12 coils off the spring. The Sound Mitigation Buffer for AR-10 rifles has an overall weight of 7.2 oz which is the equivalent of using a 4.7 oz buffer. The SMB Gen3 for AR-15 rifles is available in five different weight configurations. The list of weight options and their standard AR-15 buffer equivalents can be found below.

  • Actual Weight (Complete System):

    Carbine: 4.41 ozHeavy: 4.91 ozH2: 5.81 ozH3: 6.71 oz9MM: 9.88 oz

  • Equivalent Weight:

    Carbine: 3.3 ozHeavy: 3.8 ozH2: 4.7 ozH3: 5.6 oz9MM: 6.9 oz

AR-15 SMB Gen3 options. Left to right: Carbine, Heavy, H2, H3, 9mm.

The 9mm version of SMB Gen3 has a longer polymer end piece limiting the bolt stroke distance as well as a stronger spring. As mentioned by Armaspec, “for proper function of the SMB-9 in your 9mm rifle or pistol, the extra weight on the back of the bolt carrier needs to be removed“.

Armaspec SMB Gen3, 9mm

Both the AR-15 and AR-10 versions of Armaspec Sound Mitigation Buffer Gen3 are listed on the company’s website at an MSRP of $59.99. The choice of buffer weight will not affect the price. Extra Sound Mitigation Buffer weights can be purchased separately for $14.99. The Armaspec SMB Gen3 is made in the USA and comes with a lifetime warranty.

Pictures by Armaspec Inc.,

Hrachya H
Hrachya H

Managing Editor Being a lifelong firearms enthusiast, Hrachya always enjoys studying the history and design of guns and ammunition. Should you need to contact him, feel free to shoot him a message at

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13 of 51 comments
  • Azntactical Azntactical on Aug 31, 2022

    Though JP's captured buffer is THE best, Armaspec's Stealth buffers offer way more bang for the buck. I own 2 JP's and 5 Armaspecs for my builds. I mentally trust the JP more but one thing for sure the Armaspec's are hard to beat. My SHTF AR is still good ole' milspec buffer spring and buffer though.

  • Andrew Andrew on Sep 01, 2022

    On cutting the spring to reduce its weight by .25 lbs per coil, thats not at all how this works. They need to fire their engineer, or send him back to high school physics. Cutting coils INCREASES spring rate, but does reduce preload. While that may seem semantic, it erodes my already little confidence that this was designed to do anything but part a fool and his money.

    • See 10 previous
    • Corbin Corbin on Sep 13, 2022

      @Andrew When I have cut coils, it is usually several and I just need a different spring. I will admit I have seen pro guys trim coils for fine tuning. I think that might just be splitting hairs, but their guns do run smooth though.