AR15-----What could cause this?

StantonCree · Aug 23, 2016

Long and short I helped a buddy assemble a lower and everything was working fine when I gave it to him. I admittedly didn't have the upper to fit on it and didn't thread the buffer tube on enough so when he tossed an upper on it and charged it the Buffer Tube spring and Detent came out. Easy fix!

he is now claiming that the actual hammer when half cocked stays in place instead of falling forward. When we were doing it there was plenty of tension causing it to fall forward.

I'll admit I don't have the lower in front of me so I can't tell you a ton more but I will be removing the trigger at a later date and adding a new one just in case. Is this a spring issue? What would you all think?

UPDATE IN POST #17

GTOGUNNER · Aug 23, 2016

Where did the detent go when it came out? And no mention of the detent spring. Part still in lower?

StantonCree · Aug 23, 2016

GTOGUNNER said:
Where did the detent go when it came out? And no mention of the detent spring. Part still in lower?

No that shouldn't be the issue as he has already resolved that. It's not stuck somewhere inside the lower.

outrider58 · Aug 23, 2016

Make sure the sear spring is right side up{not sure if this will be the cause but it's the first thing i look at after seeing if the hammer spring isn't up side down.)?

Indiana Jones · Aug 23, 2016

Buffer tube threaded far enough on? If not the detent and spring will fly out and the spring will get mangled in the FCG.

StantonCree · Aug 23, 2016

Indiana Jones said:
Buffer tube threaded far enough on? If not the detent and spring will fly out and the spring will get mangled in the FCG.

That issue has been fixed but that was the initial issue but now the hammer will stay in a half-cocked position and you have to manually move it forward. It still locks in place and still goes forward when the trigger is pulled but when cocking the hammer back you can pull it back a half inch and it will stay in that position instead of the tension causing it drop forward.

if that makes sense

jimbobborg · Aug 23, 2016

Trigger spring on backward?

Mdeng · Aug 23, 2016

Is the upper attached to the lower when this happens? Is he using a full auto profile bolt? Is the hammer notched?

Fox123 · Aug 23, 2016

Sounds like it's catching the disconnector and not releasing to the sear. Check the disconnector Spring is not upside down or missing all together.

Fox123 · Aug 23, 2016

Or the trigger spring is backwards

j_h_smith · Aug 23, 2016

I think the consensus is the trigger spring is in backwards. Try that before going too deep into other possibilities.

Good Luck!

BigRick · Aug 23, 2016

lx1x · Aug 23, 2016

BigRick said:

This..

ar15 trigger can go half cock?!?

outrider58 · Aug 23, 2016

lx1x said:
This..

ar15 trigger can go half cock?!?

Yea...no. Not that I'm aware of. :cool:

lx1x · Aug 23, 2016

outrider58 said:
Yea...no. Not that I'm aware of.

clandestine · Aug 23, 2016

The Hammer Pin could be broken

The Hammer axle may be too wide and is binding in the lower

The disconnector wont release properly

The J Spring in the hammer may be broken

Grip screw may be too long causing the trigger to be tripped which means just the discconnector is catching the hammer and wont release it.

Does it have KNS Pins?

StantonCree · Aug 24, 2016

clandestine said:
The Hammer Pin could be broken

The Hammer axle may be too wide and is binding in the lower

The disconnector wont release properly

The J Spring in the hammer may be broken

Grip screw may be too long causing the trigger to be tripped which means just the discconnector is catching the hammer and wont release it.

Does it have KNS Pins?

So I just got the lower from him and will be taking it apart. He didn't accurately describe the problem.

The actual issue he has having is............

When slack is taken on the trigger it gets to a point that feels almost like a reset. It will travel back like 2cm (probably less) and then the trigger stays in that position instead of going back forward and has to be pushed manually forward.

The hammer drops just fine. When the trigger is pulled all the way everything seems to work 100%. What he is concerned about is that the trigger has to be pushed forward and does not push itself forward after being depressed a small amount.

I should have waited to post until I knew the actual problem I guess but that is his issue with the trigger.

BBossman1 · Aug 24, 2016

Sounds to me like you installed the trigger spring in the wrong orientation like others have pointed out. Pull the FCG and start over.

StantonCree · Aug 24, 2016

BBossman1 said:
Sounds to me like you installed the trigger spring in the wrong orientation like others have pointed out. Pull the FCG and start over.

Yeah I'll be doing that later this evening just in case

StantonCree · Aug 25, 2016

So I took the trigger out and installed a new one which is working fine. The trigger was installed correctly. I actually don't fully know what caused it. The trigger pulled back just fine and the hammer dropped as intended, it just would get stuck in that small creep area before the break and wouldn't go back into the forward position.

The best way to describe it would be when your shooting a glock you can pull the trigger back halfway before the reset and should you decide not to shoot the trigger will go back in its forward most position but in the AR15 trigger it would have to be manually pushed forward. I am assuming that it was to tight in the lower and the pressure of the hammer and spring pushing down on it was part of the issue. WHY? I don't know! It is however fixed. I really don't think it was a real issue because the amount of travel was so small but it he wanted it fixed.

AR15-----What could cause this?

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