AR-15 Disconnector

R

rmagill

New member
I was looking at an AR-15 lower today and I was curious:
Apart from preventing fully automatic fire, what exactly does a disconnector do and how does it do it? I tried a search but did not find anything. Sorry if this is a duplicated post. I am simply curious as to its function.

Thanks for the help.
 
The disconector holds the hammer until you release the trigger. It prevents hammer follow which is an unhealthy sutuation which may cause your rifle
to blow up in your face. :eek:
 
If you look at how the "hook" on the disconnector catches the hammer as you cock it with the lower separated from the upper you can see how it works. As previously stated, it keeps the rifle from doubling. There is a little spring that sits under the disconnector that keeps it in postion so that it catches the hammer. If someone forgets to put the spring in, the rifle will not stop with one shot.:o Once the disconnector catches the hammer and the finger tension is removed from the trigger, the hammer is held by the sear and the disconnector is not engaged.
 
Thanks for the help. That is what I was thinking would happen, but was not sure. I also did not realize it was dangerous, but now that you mention it, I can see how it is. Thanks again.
 
Not only can it be dangerous by causing a spontaneous dissassemby of your rifle (and face), it usually won't even work to create full auto. Because the hammer will ride the bolt home, it usually won't have enough speed or force to set off the primer - often resulting with a stoppage after the first round (ie. hammer down on a live round with a light primer strike. Congratulations, you just made a bolt action...). In the event that it does have enough force to fire off the round, it might fire off another round or two in full before it stops again, or it might blow up in your face.

Even if it were legal, its not worth it. Full auto can be fun, but not when its completely unreliable and potentially very dangerous to the shooter.
 
Hodaka:
I think (granted, I am the person that posted the original question, so I am kinda going out on a limb here, but I think this is correct. If I am not, please feel free to correct me) that the AR-15, in this situation, could blow up similarly to how a semi-auto handgun can blow up if it were to fire out of battery.

If the round is not fully in the chamber (which normally contains the explosion of the round) and the firing pin hits the primer (ie. from an early hammer strike from no disconnector), thus causing it to ignite, and iginte the powder inside the round, the round will "fire".

Because it is not fully in the chamber, there is would be an insufficient container for the resulting explosion. The explosion would therefore take place in the "guts", if you will, of the gun instead of the chamber, resulting in the gun "blowing up". However, this is from my knowledge of semi-auto handguns and my limited knowledge of rifles, but I think the theories are the same.
 
Well, hammer follow-down is not good for the simple reason that the gun will not fire and then you have to recock it manually. On a range, that is a nuisance; in combat it could be a bit more of a problem. In the AR-15/M16, a misfire means opening the bolt, ejecting the chambered round, and feeding another one, since (unlike the M1/M14) there is no way to recock the hammer without operating the bolt.

But as for the rifle firing unlocked, unless there is some defect it can't happen, and hammer follow-down will not result in out-of-battery fire.

The reason is that the firing pin cannot reach beyond the bolt face unless the locking lugs are turned to the locked position, and that can't happen until the bolt is fully closed, at which point the hammer does not have enough momentum to fire the round. So a hammer follow down will result only in a misfire, not in an out-of-battery fire or a "blow up."

(FWIW, some folks, who know nothing about full auto fire, assume that removal or tampering with the disconnector will cause a semi-auto weapon to fire full auto. Without going into detail, this is true for some guns, but the AR-15 is not one of them.)

Jim
 
rmagill - you nailed it; an out of battery detonation. I've seen and experienced it with pistol calibers (not too bad), but with rifle calibers it can be much more ugly. I was even unfortunate enough to be a few feet away from a friend's M2HB when it blew a .50 BMG out of battery. The heavy machined steel topcover was blown to pieces from the force - just shattered like it was glass. I found pieces the size of my little finger more than 20 yards away. Somehow, no one got hit and seriously injured by all the shrapnel. A .223/5.56 wouldn't be nearly as bad as a .50, but it sure ain't pretty. Usually the upper receiver is split apart and blown into a few pieces and the lower receiver and magwell are bulged out and damaged badly.
 
Jim, with some aftermarket AR triggers, eg., the JP, it's possible to adjust the disconnector engagement so that one gets f.a. fire. I don't believe that is because of the hammer follow that you describe, as I believe, as do you, that a true hammer follow will not likely cause f.a. fire. What I do believe is that the disconnector engagement is so light that the slamming of the bolt forward releases the hammer, much like an auto-sear might. I suppose that's why JP includes a warning against using their triggers to achieve f.a. fire. :)
 
That is a different situation, sometimes referred to as "jar off". It has been known to happen with light triggers on pistols also, the hammer falling when the slide slams forward.

Any FA system that delays hammer release until the bolt is locked at least will not be dangerous as far as out-of-battery fire is concerned. But another danger is that the nice folks at BATFE don't care what causes FA fire, if it appears to be the result of some deliberate action (i.e., not a broken/worn part).

And of course, the folks who want FA fire will read that JP "warning" as a "how to" instruction and may get into trouble.

Jim
 
Jim, I read the warning, but didn't have a clue how f.a. might occur with the JP trigger. Part of the fitting process, sometimes, is "timing" the connector by filing a little off the nose. There's a point where the disconnector will either barely catch or not catch at all, but the sear will catch. I've suffered accidental f.a. when trying to adjust all the creep out of my trigger. Quickly remedied the situation.
 
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