New AR15 build problem, 1 pull...2 bangs

[SavageGerbil]

Just finished up a build, and twice it fired...well, twice. Pulled the trigger a total of 4 times, sent 6 rounds...not good.
Anyone have this happen before? No idea what might be causing it, apart from maybe a faulty disconnector (or disconnector install?)

The first time it happened, I figured "hey, I'm firing it off a rest, maybe I didn't have it held tight enough and I accidentally bump fired it"
Second time, definitely not the case. It's not a light trigger by any means.

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[Member 34319]

If you have a spare trigger try that before anything else.

If not. I would replace the disconnector first. Then the trigger and hammer.

 

[SavageGerbil]

Typed the thread up before checking, whats happening is the hammer drops a second time when I release the trigger

 

[DirectDrive]

Check that the disco spring is installed correctly and check that the disco moves freely without binding.

 

[808hondacrguy]

I had this happen once, and it was because the trigger or hammer pin ( don't remember which one ) had walked out of place, so it was not aligned properly. Check the easy stuff first.

 

[Member 34319]

Typed the thread up before checking, whats happening is the hammer drops a second time when I release the trigger

Disconnectors are usually just stamped heat treated metal. Maybe they get an eyeball to ensure they aren't F'd up. With the prices on parts kits so low these days I'd doubt that little sliver of steel is getting a glance from some companies. I've seen plenty give folks hell off the get go and need replacement.

 

[Rcguy33]

Is this a factory lower or 80%? One of my 80% builds was doing this about every 4 to 5 trigger pulls. I replaced the entire fcg and still did it. Was recommended to try anti rotating pins, issue solved. Hasnt done it since. One of the holes must have been barely out of alignment.

 

[SavageGerbil]

Yup, trigger pin was just a tiny bit out of place. Took it apart, put it back together, and the disconnector is now doing it's job...rather than trying to be a second trigger. Thanks guys, I appreciate it. Never had that happen before

 

[EPS]

Typed the thread up before checking, whats happening is the hammer drops a second time when I release the trigger

You got a BIANARY TRIGGER.
Lol I paid $450 bucks for mine.
Seriously check the trigger to make sure all the springs are in the trigger the right way.
And if you did a trigger polish job did you do polish the right spot and or did you sand too much .

 

[EPS]

I was going to say possibly gas problem .
Getting hammer follow.
But that usually doesn't get a discharge.
Just a failure to fire and you have to pull the charging handle and eject a loaded round.

 

[SavageGerbil]

I was going to say possibly gas problem .
Getting hammer follow.
But that usually doesn't get a discharge.
Just a failure to fire and you have to pull the charging handle and eject a loaded round.

Nah, just an improperly seated trigger pin. Slightly farther to the left than is proper. It was my first time building on one of the silly polymer ATI lowers, which have a larger space on either side of the pin than is necessary. They've got little screws in the package to go over that....which I didn't use, until now.

It works properly now, nice thunk on the reset instead of the snap of a hammer falling. Back to the range tomorrow for a (hopefully) successful round 2.

 

[Kruel J]

Keep us posted on your progress.

 

[eldbillbo]

Disco spring is probably upside down. That's all you need to do get a binary trigger is flip that puppy upside down and a double whammy most of the time.

 

[EPS]

Nah, just an improperly seated trigger pin. Slightly farther to the left than is proper. It was my first time building on one of the silly polymer ATI lowers, which have a larger space on either side of the pin than is necessary. They've got little screws in the package to go over that....which I didn't use, until now.

It works properly now, nice thunk on the reset instead of the snap of a hammer falling. Back to the range tomorrow for a (hopefully) successful round 2.

I should have known that.
I did the same thing building a plastic lower.
But my problem was the safety would not work.

 

[SavageGerbil]

I should have known that.
I did the same thing building a plastic lower.
But my problem was the safety would not work.

I lucked out there, safety lever works nice and smooth. Seats and unseats with authority, functions perfect.
Honestly, this thing looks and feels pretty nice, but I'm probably not buying another poly lower unless it's an 80% to tinker with.

I'll post an update tomorrow if I find the opportunity to shoot the thing. The long range is pretty heavily populated with people sighting in for hunting season, and since it's a 10.5 AR, I don't want to use it when there's other people using the short range. Little too much blast to consider myself a good neighbor with this thing.

 

[EPS]

I lucked out there, safety lever works nice and smooth. Seats and unseats with authority, functions perfect.
Honestly, this thing looks and feels pretty nice, but I'm probably not buying another poly lower unless it's an 80% to tinker with.

I'll post an update tomorrow if I find the opportunity to shoot the thing. The long range is pretty heavily populated with people sighting in for hunting season, and since it's a 10.5 AR, I don't want to use it when there's other people using the short range. Little too much blast to consider myself a good neighbor with this thing.

I did a few polymer 80 lowers .
Lol like three of them I only got one that works.
Probably because I didn't have the right tools.
To do it.
Later I got the right tools and did it right.

Now I got the tools and stuff and did a few aluminum ones .
Lol it just takes money.
HEHEHEHE

 

[SavageGerbil]

Repair took, problem free now!

 

[308]

I had this happen once, and it was because the trigger or hammer pin ( don't remember which one ) had walked out of place, so it was not aligned properly. Check the easy stuff first.

M&P 15/22s like to do that. My grandson didn't understand why his was double tapping, but we sorted it out quickly with ARPs

 

[nwslopoke]

I had something similar with a drop in trigger. It's interesting. Fixed it but loose tolerances allowed it to happen.