selective-fire, mechanicsSomething I’ve been wondering for a while but never found anyone to ask.
How does a gun, let’s say for example, an M16 know how many shots to fire off?
I know that you can obviously change the lever on the side from safety, to semi auto, to full auto but how do the internals of the gun know how many rounds to shoot?
Cheers
Specifically for the M16 and M4, the selector can be placed into one of three positions:
Safe, Semi, Burst or Safe, Semi, Auto
To enable 3 round burst, the selector must be rotated 180 degrees from Safe. To actually “count” the number of rounds, there is a cam located at the pivot point of the hammer that rotates keeping count of the number of rounds fired. Upon completing its rotation, the cam actuates a secondary, burst disconnector that catches the hammer, limiting the number of rounds fired. After the count, the trigger must be reset by the shooter and starting the count over again if the shooter decides to fire another burst.
The burst cam, burst cam spring and burst connector in the M16 and M4 are extra parts added on top of the full auto fire-control group and arguably adds complexity and reduces the reliability of the system.
All content is licensed under CC BY-SA 3.0.