AR15 failure to fire

[Skeet375]

A friend of mine is having a problem with his AR not re-setting the trigger during firing. It started out doing it maybe once out of 100 shots but has progressively gotten worse. Last weekend it got to the point to where it did it 3 or 4 times per 20 round mag.
It chambers the next round no problems but when you pull the trigger the gun is not cocked and you must manually jack another round in to get it to reset.
It never fails to set during initial cocking of the gun and he could not make it happen while manipulating the hammer and trigger by hand. Looking at it, everything "seems" to be in order.
The gun is an Olympic arms lower with a GG&G Dominator upper. I believe it has a Jewell trigger.
Any thoughts on what might cause this?

 

[Jboeri]

Re: AR15 failure to fire

Sounds like it's either short stroking or an issue with the sear being worn down. Try some heavy loads and if that doesn't do it take a hard look at the contact points on the trigger.

 

[bama110]

Re: AR15 failure to fire

swag is weak load? dirt in buffer tube causing bolt to not go all the way back?

 

[LoneWolfUSMC]

Re: AR15 failure to fire

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jboeri</div><div class="ubbcode-body">Sounds like it's either short stroking or an issue with the sear being worn down. Try some heavy loads and if that doesn't do it take a hard look at the contact points on the trigger. </div></div>

It takes less movement of the BCG to cock the trigger than it does to strip a fresh round.

I would take a look at the disconnector and BE VERY CAREFUL. If the hammer is following the bolt carrier you can end up with a runaway gun.

 

[Skeet375]

Re: AR15 failure to fire

He's going to take a look at the disconnector tonight and see what the deal is. It sounds like the hammer is following the bolt as there is a mark on the primer of the round it picks up.

 

[afd77]

Re: AR15 failure to fire

Definitely sounds like a problem with the disconnector. There is no way for the bolt to go back far enough to strip the next round without it forcing the hammer back. Sounds like it's just not catching. As said above, I would be very careful around this gun.

I would take the upper off and function check the trigger assembly. Release the hammer and keep holding the trigger while you manually reset the hammer and see if it catches.

 

[ErikS]

Re: AR15 failure to fire

the mark on the primer happens on every chambered round in an AR. The floating firing pin does it and it is normal. If the weapon is stripping a new round then the problem is in the FCS, replace the trigger with a milspec type and see what happens. It will be a crappy trigger but for testing purposes it will be an easy check.

 

[samnev]

Re: AR15 failure to fire

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jboeri</div><div class="ubbcode-body">Sounds like it's either short stroking or an issue with the sear being worn down. Try some heavy loads and if that doesn't do it take a hard look at the contact points on the trigger. </div></div>

It takes less movement of the BCG to cock the trigger than it does to strip a fresh round.

I would take a look at the disconnector and BE VERY CAREFUL. If the hammer is following the bolt carrier you can end up with a runaway gun. </div></div>

+1 on that.

 

[Skeet375]

Re: AR15 failure to fire

We got to looking at the disconnector and it looks like the adjustment screw backed out a little. When it was backed out more the problem got a lot worse. So we adjusted it in and put some lock-tight on it. He will try and test fire it tomorrow.