Can anyone explain how 3 round burst works?  (on any platform really)  



I've just been thinking about it.   It barely makes any sense to me.   I don't have an MG nor do I plan on getting one in the near future.    Just curious.   I don't need detailed drawings as I'm not looking to commit any felonies today.   Just hoping someone can explain it in layman's terms.  

When set to burst, the m16 has a ratchet (burst cam) inside the trigger group that counts 1-2-3 stop 1-2-3 stop over and over again.
Hold the trigger to the rear, and the burst cam allows the auto sear to fire 3 shots. If you interupt the cycle, the cam is left in the mix of where it left off counting. If you fired two rounds, the next press of the trigger gets you one shot and then resets back to the begining.

He's pretty much somed it up.  The burst cam turns each time the sear is struck by the bolt carrier and the hammer is let go by the dissconecter.  On the third strike, the cam resets and the sear falls into a position that makes it impossible for the bolt carrier to engage with it, the dissconect catches the hammer and the cycle of fire stops.  
Like stated above, the cam doesn't reset with each let off of the trigger, so where ever you left off is where you begin with the next course of fire.

the 3-round burst works similarly on the Ruger AC-556 series, but Heckler & Koch's version which resets and gives you 3 shots each and every time is markedly different...

Yeah, the HK's is like a damn swiss watch.

Dont know how true it is but someone a long time ago told me  that the Swiss actually helped design the HK platform

What about the 3 round burst kits for AKs?

No idea if the swiss helped them, I could see it happening. AK 3rd burst? Is there such a thing? In soviet russia, AK burst you!!!

Yeah I never heard of burst packs in an AK.  The Russians just gave their troops a few mags of ammo and told them they were dead if they ran out so use them wisely....  That was about the extent of their 3 round burst.

AK-74 3 round burst

I cant tell but it doesnt look like it would reset itself after only 1 or 2 rounds fired. Whacha think?

looks like a non-resetting 3rd burst to me - mechanical equivalent of the M16A2 3rb fcg.

The Polish wz.88 Tantal (an AK-74 clone) was equipped with 3-round burst.

As far as the M16, there is a pretty good explanation/diagrams of burst function in the military's 23P level manual starting on page 108. (I know the OP didn't ask to go that far, but someone as technical as myself will want to read it. Your tax dollars at work.)
The way I usually explain it to people is that there are 2 disconnectors in a burst FCG, as opposed to the 1 normally found in an auto (or semi-auto) FCG. The first disconnector does the full auto function, and the second forces a disconnect when the burst cam tells it to, which could be after 3 rounds (if it was indexed to begin with).