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AR15.COM
10/6/2008 5:23:00 PM EDT
Ive never been able to figure this one out. How does a mechanical device like an ar, know when 3 shots have been fired? What stops it from cycling?
10/6/2008 5:25:50 PM EDT
[#1]
there are 2 pieces in the trigger one is a standard disconnect the other rides on a cam that is on the side of the hammer.

After 3 shots it resets.

10/6/2008 5:26:24 PM EDT
[#2]
cam
10/6/2008 5:27:26 PM EDT
[#3]

Quoted:
Ive never been able to figure this one out. How does a mechanical device like an ar, know when 3 shots have been fired? What stops it from cycling?


It's FM.
10/6/2008 5:30:05 PM EDT
[#4]

Quoted:
there are 2 pieces in the trigger one is a standard disconnect the other rides on a cam that is on the side of the hammer.

After 3 shots it resets.



But how does it know 3 shots have gone by?
10/6/2008 5:31:05 PM EDT
[#5]
there is a deeper slot in the cam on the 3rd shot that will trip the sear to reset the hammer
10/6/2008 5:31:37 PM EDT
[#6]
See the round thing with the ratchet teeth on the right side of the picture? That is the part that resets the semi-auto sear after it rotates and clicks three times.


10/6/2008 5:33:05 PM EDT
[#7]
From what I've seen in the 3-round burst trigger groups there are 3 disconnectors. After all three have cycled, the last one stops the hammer and you have to pull the trigger again to repeat the process. If I'm wrong someone will correct me.
10/6/2008 5:33:11 PM EDT
[#8]
also, if you hold the trigger down just long enough to fire one round, the next time you pull the trigger, only 2 rounds will fire.

im sure someone has a pic of the aforementioned cam somewhere

eta: 57 got it
10/6/2008 5:35:31 PM EDT
[#9]

Quoted:
there is a deeper slot in the cam on the 3rd shot that will trip the sear to reset the hammer


cool makes sense now,
Thanks
10/6/2008 5:40:49 PM EDT
[#10]

Quoted:
See the round thing with the ratchet teeth on the right side of the picture? That is the part that resets the semi-auto sear after it rotates and clicks three times.


www.ftfindustries.com/m163shot.JPG


There are 2 disconnects, one for semi, identical to the civy version.  The other with a forward hook which only lets the burst disconnect trap the hammer after 3 rounds.  There is a sprag clutch on the cam which lets it rotate in one direction only.  After each round, it rotates 1/3 turn. On the 3rd round, the cam is cut lower, letting this burst disconnect catch the hook on the hammer.  Reset is by releasing the trigger fully.
10/6/2008 5:41:00 PM EDT
[#11]
In HK weapons, the mechanism is different.  With a HK, the 3 round burst mechanism is reset when you release the trigger, even if you've only fired 1 or 2 shots.  If you pull the trigger again after firing 1 or 2 shots, you'll always get 3.  
10/6/2008 5:46:26 PM EDT
[#12]
Hey, how exactly is a rainbow made?
                 
How exactly does the sun set?
                 
How exactly does the posi-trac
rear end on a Plymouth work?
                 
It just does.
10/6/2008 5:46:29 PM EDT
[#13]

Quoted:
there is a deeper slot in the cam on the 3rd shot that will trip the sear to reset the hammer


DISCONNECT!  The AUTOsear is positioned by the selector. In semi, the AUTOsear is cammed out of the way so as not to catch the hammer.  The tail of the semi DISCONNECTOR is positioned to allow it to catch the disconnect surface of the hammer.  

10/6/2008 5:47:05 PM EDT
[#14]

Quoted:
Hey, how exactly is a rainbow made?
                 
How exactly does the sun set?
                 
How exactly does the posi-trac
rear end on a Plymouth work?
                 
It just does.


Anything you say Mr. Nunnamaker!
10/6/2008 5:47:45 PM EDT
[#15]
It messes up your semi auto trigger pull too, since each pull varies in weight as the cam cycles.  Not bad... but when trying to do precision it can throw you off.
10/6/2008 5:51:53 PM EDT
[#16]

Quoted:

Quoted:
Hey, how exactly is a rainbow made?
                 
How exactly does the sun set?
                 
How exactly does the posi-trac
rear end on a Plymouth work?
                 
It just does.


Anything you say Mr. Nunnamaker!


LOL, I was wondering if anyone woud catch that
10/6/2008 5:53:33 PM EDT
[#17]

Quoted:

Quoted:

Quoted:
Hey, how exactly is a rainbow made?
                 
How exactly does the sun set?
                 
How exactly does the posi-trac
rear end on a Plymouth work?
                 
It just does.


Anything you say Mr. Nunnamaker!


LOL, I was wondering if anyone woud catch that


I really wanna watch some joe dirt now.