AR-15 Buffers Explained by Small Arms Solutions LLC

Chris Bartocci of Small Arms Solutions LLC has released a video, where he reviews the different types of AR-15 buffers. He discusses the evolution of the buffers in chronological order. Starting from M16 buffers and the first appearance of bolt carrier group bounce issue all the way to 9mm buffers. There are also a couple of experimental unicorns in the video such as the Colt’s prototype hydraulic buffer which never went into production. He also tells about the possible dangers and malfunctioning issues in different climate conditions when using improper buffers.

AR-15 Buffers - SAS

Another interesting subject is how the carbine barrel weight is related to the buffer weight. In a nutshell, the heavier barrel you have, the heavier buffer you need to use. The designation meaning and proper use of different weight AR-15 carbine length buffers are also pretty well explained. It is basically as follows:

  • Unmarked (three steel weights inside the buffer). This is the standard .223/5,56 semi auto only direct impingement carbine buffer.
  • H (one tungsten weight with two steel weights). This buffer is also for the rifles as the unmarked one with probably a bit improved reliability.
  • H2 (two tungsten weights and one steel weight). H2 buffers are better when used with heavy barrels and long or short stroke piston operated carbines.
  • H3 (three tungsten weights). This one was designed to work in Colt IAR, which has a longer and heavier barrel compared to the carbines. H3 is recommended to be used with that kind of barrels.

The correct choice of proper weight buffers is especially important in full-auto capable rifles.

Chris also discusses the different kinds of 9mm buffers and a lot more. So if you find this subject interesting, you can learn more by watching the video:

Hrachya H

Being a lifelong firearms enthusiast, Hrachya always enjoys studying design, technology and history of guns and ammunition. His knowledge of Russian allows him to translate and make Russian/Soviet/Combloc small arms related information available for the English speaking audience.
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  • iksnilol

    AR buffers and buffer weights: Basically witchcraft.

  • It should have been titled M-16 buffers since the discussion is relevant to full auto operation more than AR-15s. He also has an issue with his materials and miss identifies the H3 buffer as having 1 tungsten weight instead of 3 (the verbal is correct). I believe the discussion of buffer dynamics and interaction with keeping the carrier closed from rebound is slightly off. Discussion of buffer mass with overall system mass constraints would have been good to include with this discussion as well. Overall good video on showing the range of buffers.

  • NewMan

    Actually, buffer weights is more related to gas port size and gas length rather than “barrel weight”.

    • Paul Joly

      Spring and damping system too.

    • Marcus D.

      I read that and thought to myself, “Whaat?” The thickness of the barrel has nothing to do with internal pressures that are dependent on the factors the others in this comment have mentioned–at least to someone like me with no technical knowledge.

    • Dave L

      When it comes to nonsensical conjecture, you gotta consider the source;)

    • Dave L

      It can be demonstrated by the math, that as the inertia of a rifle is reduced, its operating system must be adjusted to move more readily (BCG and buffer mass/inertia must be reduced). In effect, a rifle can “short stroke” itself. All the events in the cycle must happen in order, and in time. This short stroke issue only comes up when you’re making a really light rifle- the BCG and buffer must follow suit. As you increase the mass of a rifle, the system’s sensitivity to recoiling mass drops off. The gun seems to care less and less. I engineered a rifle called the OIP. I have a bit of this well understood.
      …And The H3 in the IAR is used ONLY for rate control.
      …When it comes to nonsensical conjecture (the video), you gotta consider the source;)

  • Gary Kirk

    Tried to watch, but the video kept “buffering”…

    I’m done now..

  • BrandonAKsALot

    From a purely physics standpoint, how can the barrel weight affect your buffer weight necessity in any way? That makes no sense whatsoever. Now, barrel length, sure. A heavy barrel does nothing to affect the force applied to the bolt carrier, so I don’t get that.

  • Frank Grimes

    Barrel weight has absolutely nothing to do with what buffer is correct for your rifle.

  • lol

    Uhh what does buffer weight have to do with barrel weight? I did not watch the video, but your translation is completely off base and incorrect. If this were true, SBR’s would all be using car buffers instead of H3 or vltor A5H4’s. Buffer weight is directly correlated to gas drive, which is affected by barrel LENGTH, gas port size, and gas port location/gas system length. Ammunition and muzzle device as well to a lesser extent.

  • marine6680

    Interesting info.

    My question, is this info only applicable to 14.5″ carbine length rifles?

    It would seem that the variables of a 16″ barrel and mid length gas system, in addition to the large amount of variation in gas port sizes you can encounter. Some manufacturers throw in a standard buffer just for cost savings as well.

    For example… A PSA modlength 16″ carbine might need an H2 to prevent issues with early unlocking. Maybe the same for other brands.

    But I do think the advice of how rifles behave differently between warm and cold weather is important.

  • Scott Tuttle

    when he says barrel weight I’m replacing that in my head with barrel length. whats the deal with his body armor? some kind of reloading protection?

    • Wolfgar

      It’s a back brace, he broke his back.

      • Scott Tuttle

        ahh ok.

  • Lots of posts asking why barrel weight has any effect. That was my thought too, but the video kinda answers that question. From what I could gather, it sounds like it has to do with inertia. A heavier barrel has more inertia moving backwards with recoil, which requires a heavier buffer to counteract that inertia to prevent bolt bounce. In the video he said they were getting a lot of bolt bounce and light strikes when they went to the heavier M4A1 barrel, before they added more weight to the buffer with what became the H2 buffer. Good video.

    • I would argue that the system would’ve already been borderline H2 if that little weight was enough to cause bolt bounce.

      The M4A1 barrel is only 4oz heavier.

    • Marcus D.

      How can the bolt bounce if it is supposed to lock in to the chamber when it reaches the end of its forward motion? Further, a heavier barrel has more inertia, and therefore moves back (slightly) less than a lighter barreled firearm since it does not accelerate as much backwards after a shot is fired. The buffer only buffers the bolt, not the rifle.

      • jcitizen

        Some variants of the AR don’t need bolt lockup, but of course those calibers are not the scope of this article.

  • Swarf


  • CavScout

    I’d prefer an optimally gassed rifle with a standard buffer ANY DAY over overgassing with a heavier buffer. With BRASS ammo.

  • uisconfruzed

    This was educational, thanks for posting!

  • Bill

    He wore me out!

  • Dave L

    Yes. Agree.