How the M-16 3-Round Burst Works

Most military members take the arcane workings of their rifle for granted. Even an avid shooter myself, I was NEVER allowed to do maintenance on my M-16 fire control group while I was in the Corps. While some might argue this is a good thing considering that many members of the military are not interested in firearms, I firmly believe that everyone should know their weapon inside and out – especially if there is an issue.

Rant over, YouTuber Stealth the Unknown has taken the time to create a fantastic video showing how the 3-round burst works. He builds up from semi-auto, to full-auto, and finally to the burst function.

The more you know…

*Title photo from ARFCOM. 

Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • Squirreltakular

    Nothing pisses off high-level SNCOs like showing all the boots in your squad how to diss n’ ass and clean the trigger group of their rifle responsibly.

    • Firehand

      Just before graduating Basic, when they were supposed to clean their rifles before turning in, son figured out how to remove the trigger assembly so he could give it a real cleaning.

      Also made money charging others to do it when they saw he could do it.

  • iksnilol

    Cue the military guys who hated the 3-round burst.

    • Riot

      Does anyone like it?

      • Joshua

        No one likes having 3 different trigger pull weights.

    • Esh325

      It can’t be very well liked if they are converting 3 round burst M4’s to full auto trigger groups. My understanding is that the 3 round trigger group can result in a poor semi auto trigger pull some times. The 3 round burst mechanism in the M16 isn’t really the most well thought out. One guy in the Marine Corps I talked to said the first two shots would be on target while the 3rd would be off target he said. He said he would prefer a 2 round bust.

      • Squirreltakular

        The Russians seem to like 2 round burst.

        • Esh325

          They do. I believe they recently switched the AK-12 from a 3 round burst to a 2 round burst.

          • Joshua

            Pretty sure the AK-12 ended up not getting adopted force wide. Russia showed off their new AK-74’s during the parade and said it was their new rifle.

          • Esh325

            I honestly have no clue what they will actually do because there are so many inconsistencies. They say one day they will adopt the AK-12 then the other day they say they won’t adopt the AK-12, then they say they will. They might not even update their AK-74’s for all we know.

          • Giolli Joker

            Search for the interview of Kalashnikov CEO here on TFB and you get more answers. 😉

    • Miles

      Yes, when my unit drew M16A2s, we quickly came to despise the 3 round burst.
      We were lucky though. Since ROTC holds their final ‘summer camp’ at Ft Lewis, they still used M16A1s and at the time, we were their smallarms repair support and had mass quantities of M16A1 fire control parts still on hand.
      Our Platoon Sergeant had many years experience and said if wanted a 3 round burst, he could do it, but if he wanted to empty a magazine, he wanted to do that as well.
      After his issued rifle mysteriously had the burst parts changed out we could do no wrong in his eyes from then on.

  • UCSPanther

    This is something that the M2 carbine could have benefited from.

  • nadnerbus

    So basically, if you had a three round burst trigger group, you could remove or cut down the burst disconnector and it would just revert back to standard full auto?

  • Joshua

    It still has a different trigger pull depending on the tooth of the cog you are on. This is well known by everyone.

    Inconsistent trigger pulls lead to inconsistent accuracy.

  • Martin Grønsdal

    I have never fired an M16 with the three round jurst: will the mechanism increase the semi auto trigger pull weight?

    As far as soldiers playing with delicate parts in a rifle? With career options ranging between McDonald’s and Army…. don’t touch it….

  • john

    Very well thought out video. Really clear description and animation. I am glad I watched it.

  • Squirreltakular

    It’s obviously possible, and it may take a certain amount of skill to shoot a weapon well when it has a bad trigger, but no one can make the argument that an A2 trigger group is equal to a Geissele SSA.

  • MrEllis

    Avert your eyes! It is forbidden! Aaaaaaaaaaaah!

    Also, neat write-up, thanks.

  • Well done video. But, as long as the bolt face is clear of debris and in-spec ammo is used, it’s impossible for an AR15 to fire out of battery (4:20).