AR15 Failure to fire 2nd round issue

[ar15barrels]

Either the trigger is binding, keeping the trigger spring from re-setting the trigger, or the spring is installed incorrectly.

Try this test:
After you fire the first round, manually pull the trigger forward.
Now you should be able to fire another round.

When you put the safety on, you are using the safety selector to reset the trigger.

[showerbabies]

Either the trigger is binding, keeping the trigger spring from re-setting the trigger, or the spring is installed incorrectly.

+1

I had the same exact problem. Turned out that I was holding on to the trigger just a nanosecond too much. Instead of shooting with the "pit" of your finger, try using just the TIP.

[diginit]

+1

I had the same exact problem. Turned out that I was holding on to the trigger just a nanosecond too much. Instead of shooting with the "pit" of your finger, try using just the TIP.

Holding the trigger too long doesn't make sense to me.
The round fires sending the bolt back and the hammer is caught by the disconnector. The disconnector will hold the hammer clear of the bolt until the trigger is released. You can hold it for an hour if you like.
When the trigger is released, the hammer drops about 1/4" into the cocked position and is caught by the sear on the front the trigger assembly. Pull the trigger and the hammer drops to the firing pin.
Repeat as necessary. It sounds to me like your disconnector is not engaging.
Notice any excess wear on the carrier or hammer?

Drill 2 holes in a block of metal or wood to match the hammer and trigger pins. ( you can use the outside of a reciever,but it may scratch it. Use a stripped reciever an a template) And assemble,test the firing control group. like this:

The sear(dead center of the pic) should catch the sharp tang just under the hammer face when the trigger is held back. Release the trigger and it should drop to the position shown. and release the hammer when pulled. Install the springs for a true test.

[diginit]

Here's one for Timsar:

[SKG19]

Don't know what exactly is wrong. I'm sure the other guys have answered the question. But, this is the main reason why I'm glad I bought a stripped lower and put it together, as I think it give one a much better understanding on how the mechanism works and possibly the ability to trouble shoot it. It probably also helps I'm a mechanical engineer by training.

I would suggest anyone who's reading this thread who's thinking about getting an AR. Buy a stripped lower and put it together yourself, you won't regret it.

Before anyone gets their panties in a bunch, I'd just like to say I'm not judging anyone, just giving advice to newbies.

[SKG19]

Here's one for Timsar:

Is it just me or does it seem like the disconnecter spring is missing.

[jrsportssupply]

It looks that way to me too, but leaving out the disconnector spring causes a VERY different malfunction.

[diginit]

The disconnector spring and rubber insert are under the disconnector on this LPK. between the trigger housing and the disconnector. It is a small coil spring.

[ar15barrels]

The disconnector spring and rubber insert are under the disconnector on this LPK. between the trigger housing and the disconnector. It is a small coil spring.

There's no rubber insert on the disconnector.

[ar15barrels]

Holding the trigger too long doesn't make sense to me.
The round fires sending the bolt back and the hammer is caught by the disconnector. The disconnector will hold the hammer clear of the bolt until the trigger is released. You can hold it for an hour if you like.
When the trigger is released, the hammer drops about 1/4" into the cocked position and is caught by the sear on the front the trigger assembly. Pull the trigger and the hammer drops to the firing pin.
Repeat as necessary. It sounds to me like your disconnector is not engaging.

Disconnector is engaging fine.
The trigger is not resetting when released.
Could be a tight fitting trigger that's binding.
Could be a weak trigger spring.
Could just be a bad trigger that does not fit the lower correctly.
In any case, his moving the selector to safe is resetting the trigger and allowing it to fire after he removes it from safe.
That means the disconnector has to be working correctly or the hammer would be down on the carrier and would not fire after going to safe and back to fire.

[jgraham15]

The disconnector spring and rubber insert are under the disconnector on this LPK. between the trigger housing and the disconnector. It is a small coil spring.

Wow, that sounds like the extractor spring!

[diginit]

ar15barrels,

This was in response to Showerbabies post in this thread. He stated he was holding the trigger too long.
I should have said that I added the insert for a little stiffer disconnector spring. Haven't tried it yet. I wanted alittle quicker disconnect. Still grabs the hammer easily. Is this a good or bad idea. I'm fairly new with the Oll's. But have done other trigger jobs. I like mechanical things. I'm also working on a female robot. With an on/off switch.

[ar15barrels]

ar15barrels,

This was in response to Showerbabies post in this thread. He stated he was holding the trigger too long.
I should have said that I added the insert for a little stiffer disconnector spring. Haven't tried it yet. I wanted alittle quicker disconnect. Still grabs the hammer easily. Is this a good or bad idea. I'm fairly new with the Oll's. But have done other trigger jobs. I like mechanical things. I'm also working on a female robot. With an on/off switch.

There is never a problem in disconnecting that a rubber insert would help so you should remove it.
The problem is that the trigger is not properly resetting.
The disconnector is always going to hold the hammer until such time that the trigger captures the hammer and the disconnector releases the hammer to the trigger's control.
That's called hammer hand-off.

[Creampuff]

Posted these pics a while ago, don't know if it will help your situation:

http://www.calguns.net/calgunforum/showthread.php?t=32797

[Sky_DiveR]

I've read this entire post and perhaps this might be a stupid question, but... would lack of lubrication prevent the trigger from returning after you fire a round and release the trigger? I haven't built an OLL and therefore do not know the tolerances for the trigger assembly. If there is a lack of lubrication, would the trigger return spring be strong enough to overcome the resistance? Or perhaps the lubrication dried up from prolonged storage? Doesn't oil get sticky after a few years from lack of use?