AR-15 Trigger Reset?

[ZigZagZeke]

Well, I've finally gotten around to testing the Palmetto State AR that I built from the kit I won here on NWFA. I've had it at the range for the last two days and all the kinks are ironed out except one. It will cycle, eject a spent round and load a new one, however, the trigger does not reset. I rearranged the gas rings on the bolt and lubed the heck out it with CLP, but still no trigger reset. I have not yet gotten into the buffer to see what's going on. Any hints from you guys about that? Any other suggestions would be greatly appreciated. I'm probably going to get into the buffer and see what's going on there in a day or two. I was really careful make sure the gas block was lined up properly. I really do think it's getting enough gas. The action seems pretty stiff and rough compared my Bushmaster. Maybe it just needs breaking in. I've put about 100 rounds through it so far. Thoughts?

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[Oathkeeper1775]

When you indicate "reset", do you mean it does not lock back in the ready position after firing?

 

[Stomper]

Conduct the manual of arms for a function test of the safety selector and trigger reset:

Does the trigger reset after you manually cycle charging handle? If yes, then you most likely have an under-gass, or buffer assembly situation, or both during live-fire. It may also just need a break-in.

If the trigger doesn't reset the safety shouldn't be able to engage, if it does engage push out the rear take-down pin and break open the upper to see if the hammer is forward. If it is forward then you may have a faulty sear or incorrect installation of the LPK assembly, and the safety selector DEFINATELY has issues.

Can you push the hammer to the rear and lock it into place with your thumb? If yes, did the trigger reset? If not then your sear has issues or the LPK has issues.

If everything above checks out....



Conduct a live-fire function test of the safety selector and trigger reset:

Chamber one round, drop the magazine, fire the rifle so it'll cycle (w/o locking the bolt to the rear), then attempt to put the weapon on safe.

If DOES NOT go into safe the hammer should be forward and you most likely have an issue with undergassing, the sear, the buffer assembly, or a combination of all three.

If the weapon DOES go into safe the hammer should be locked to the rear.

Push out the rear take-down pin and "break open" the upper from the lower.

If the hammer is forward you may have an issue with the sear AND the safety selector (if it engages). If the hammer is locked to the rear and the trigger did not reset then you have a faulty sear or an incorrect installation of the LPK assembly.

I had a friend who built an AR with all new parts and it wouldn't fire a round no matter what he tried. We were out in the field target shooting so I took it apart and "tweaked" the hammer spring and BANG, he was in business for the day. He later replaced the spring with a new one and he's been good to go since.


Hope that helps!

 

[308]

Did you install the trigger parts yourself?

 

[Tomahawk67]

I would say the disconnector spring is probably in upside down. The flare goes down into the trigger to hold the spring from flagging.

 

[HB of CJ]

Answer already given by Stomper and thank you. A short answer that might end up long. My Bad.

Make sure the gun is empty. Place the muzzle down between your feet. Charge and squeeze. The hammer should drop. Keep the trigger squeezed down. Use the charging handle to re cock the rifle. Then release the trigger. You should feel and hear a distinct "click" when the disconnecter resets.

IF YOU DO NOT HEAR OR FEEL ...

If you do not feel and hear the reset "click" remove the top end. Place your thumb in front of the hammer so it will not chew up the bolt stop. Manually cock the hammer all the way back WHILE SQUEEZING the trigger. Then release the trigger. Catch the hammer with your thumb IF IT DROPS. Might sting.

THE HAMMER DROPPING IS NOT GOOD ...

Home build. Oh boy. If the disconnecter is not re connecting, pull out the hammer trigger disconnecter safety group and eye ball them. You might have left out the disconnecter spring. Also it is possible the bolt stop spring was installed by mistake and the bolt stop has the disconnecter spring. Happens.

The fire control group must have compatible parts. All must work together. It is possible to install some springs backwards. A design weakness. Re install correctly and place back into the lower. The safety must hold back the trigger with no slop what so ever when placed on SAFE. The parts might be rough.

Retest for the disconnecter function. You must feel and hear a distinct "click" of the disconnecter resetting. Most always with proper parts and spring location the group will function fine as designed. Watch the hammer. It will move slightly to the rear when pulling the trigger. Normal with stock parts. Do the following. ...

Heavily lube up everything. .... Heavy. Dripping heavy. Carrier and buffer also. Also the fire control group. Bolt head.

Reassemble correctly. Make sure the rifle is empty. Place the muzzle between your shoes. Hand rack the rifle. Squeeze the trigger. Hold it down. Recharge. Release the trigger. "Click". Then dry fire. Repeat about 100 times. FAST. You will smell hot metal. Take down and remove the gray sludge.

You have just lapped in the action group. Dry firing the gun 100 times will NOT hurt it. You already mentioned the rest of the home build looks good. This post addresses the fire control group function and hand lapping. It does not address short stroking or under gassing. Different subject. Hope this helps.

We will leave out barrel indexing and head space for another post. Be sure to remove all the sludge. Re lube heavy. New build.

Respectfully. Hundreds of AR15 builds. Uncounted M16 rebuilds. Long ago, far away. Now an Old Coot. Old. Very Old. Shiet.

 

[Tomahawk67]

So what was the cause of the malfunction?

 

[KKG]

Excess CLP isn't a good idea. It's a dirt/crud magnet and can slow down the functioning.

 

[ZigZagZeke]

When you indicate "reset", do you mean it does not lock back in the ready position after firing?

Yes, it does everything it should except cock (reset) the trigger.

 

[ZigZagZeke]

Conduct the manual of arms for a function test of the safety selector and trigger reset:

Does the trigger reset after you manually cycle charging handle? If yes, then you most likely have an under-gass, or buffer assembly situation, or both during live-fire. It may also just need a break-in.

If the trigger doesn't reset the safety shouldn't be able to engage, if it does engage push out the rear take-down pin and break open the upper to see if the hammer is forward. If it is forward then you may have a faulty sear or incorrect installation of the LPK assembly, and the safety selector DEFINATELY has issues.

Push out the rear take-down pin and "break open" the upper from the lower.

Can you push the hammer to the rear and lock it into place? If yes, did the trigger reset? If not then your sear has issues or the LPK has issues.

If everything above checks out....



Conduct a live-fire function test of the safety selector and trigger reset:

Chamber one round, drop the magazine, fire the rifle so it'll cycle (w/o locking the bolt to the rear), then attempt to put the weapon on safe.

If DOES NOT go into safe the hammer should be forward and you most likely have an issue with undergassing, the sear, the buffer assembly, or a combination of all three.

If the weapon DOES go into safe the hammer should be locked to the rear.

Push out the rear take-down pin and "break open" the upper from the lower.

If the hammer is forward you may have an issue with the sear AND the safety selector (if it engages). If the hammer is locked to the rear and the trigger did not reset then you have a faulty sear or an incorrect installation of the LPK assembly.

I had a friend who built an AR with all new parts and it wouldn't fire a round no matter what he tried. We were out in the field target shooting so I took it apart and "tweaked" the hammer spring and BANG, he was in business for the day. He later replaced the spring with a new one and he's been good to go since.


Hope that helps!

A big thank you for all of that info, Stomper! Yes, the trigger does reset if you manually charge the weapon. If I fire a shot with a full magazine it will eject the spent round and load a new round. It will not then fire because the trigger did not reset (it's not cocked). If I then pull the charging handle and eject the new round and let it load another round it will then be ready to fire. I'm going to make sure that the gas block is lined up properly first. I can't believe it's not because I was very careful to mark the positions and line up my marks. After that, I will be checking the buffer spring, as you suggest. Lastly, I will take a look at the trigger. I have my Bushmaster to compare it to.

 

[ZigZagZeke]

Did you install the trigger parts yourself?

Yes, but I have done quite a bit of gunsmithing and was an instrument tech for 20 years. I'm used to small parts and springs, etc.

 

[ZigZagZeke]

I would say the disconnector spring is probably in upside down. The flare goes down into the trigger to hold the spring from flagging.

Thank you! That's something I will check in the next couple of days.

 

[ZigZagZeke]

Answer already given by Stomper and thank you. A short answer that might end up long. My Bad.

Make sure the gun is empty. Place the muzzle down between your feet. Charge and squeeze. The hammer should drop. Keep the trigger squeezed down. Use the charging handle to re cock the rifle. Then release the trigger. You should feel and hear a distinct "click" when the disconnecter resets.

IF YOU DO NOT HEAR OR FEEL ...

If you do not feel and hear the reset "click" remove the top end. Place your thumb in front of the hammer so it will not chew up the bolt stop. Manually cock the hammer all the way back WHILE SQUEEZING the trigger. Then release the trigger. Catch the hammer with your thumb IF IT DROPS. Might sting.

THE HAMMER DROPPING IS NOT GOOD ...

Home build. Oh boy. If the disconnecter is not re connecting, pull out the hammer trigger disconnecter safety group and eye ball them. You might have left out the disconnecter spring. Also it is possible the bolt stop spring was installed by mistake and the bolt stop has the disconnecter spring. Happens.

The fire control group must have compatible parts. All must work together. It is possible to install some springs backwards. A design weakness. Re install correctly and place back into the lower. The safety must hold back the trigger with no slop what so ever when placed on SAFE. The parts might be rough.

Retest for the disconnecter function. You must feel and hear a distinct "click" of the disconnecter resetting. Most always with proper parts and spring location the group will function fine as designed. Watch the hammer. It will move slightly to the rear when pulling the trigger. Normal with stock parts. Do the following. ...

Heavily lube up everything. .... Heavy. Dripping heavy. Carrier and buffer also. Also the fire control group. Bolt head.

Reassemble correctly. Make sure the rifle is empty. Place the muzzle between your shoes. Hand rack the rifle. Squeeze the trigger. Hold it down. Recharge. Release the trigger. "Click". Then dry fire. Repeat about 100 times. FAST. You will smell hot metal. Take down and remove the gray sludge.

You have just lapped in the action group. Dry firing the gun 100 times will NOT hurt it. You already mentioned the rest of the home build looks good. This post addresses the fire control group function and hand lapping. It does not address short stroking or under gassing. Different subject. Hope this helps.

We will leave out barrel indexing and head space for another post. Be sure to remove all the sludge. Re lube heavy. New build.

Respectfully. Hundreds of AR15 builds. Uncounted M16 rebuilds. Long ago, far away. Now an Old Coot. Old. Very Old. Shiet.

Wow! Thank you VERY much. I will be following your instructions, and those from Stomper sometime in the next few days. It's always possible that I got a spring in backwards or swapped a couple springs. The photos in the instructions were none too clear.

I have built very high end, highly customized and tricked out semi-auto paintball guns in the past. It's very similar stuff. I rarely screw up, but it's been known to happen.

 

[JeremyK]

Silly question: do you have an aftermarket single stage trigger in it?

 

[308]

Yes, but I have done quite a bit of gunsmithing and was an instrument tech for 20 years. I'm used to small parts and springs, etc.

Will it re-set manually? Curious is the bolt carrier is riding over the hammer in such a way as it does not push the hammer down far enough.

Strange things happen. I bought a new FA bolt carrier from a co-worker and it would not rid back over the hammer. Put my old carrier in and no problemo.

 

[ZigZagZeke]

Will it re-set manually? Curious is the bolt carrier is riding over the hammer in such a way as it does not push the hammer down far enough.

Strange things happen. I bought a new FA bolt carrier from a co-worker and it would not rid back over the hammer. Put my old carrier in and no problemo.

Yes, the trigger does reset on a manual charge.

 

[308]

Yes, the trigger does reset on a manual charge.

...but not when the bolt rides over the hammer?

 

[ZigZagZeke]

...but not when the bolt rides over the hammer?

Exactly.

 

[308]

Exactly.

Well there you go

 

[Oathkeeper1775]

One additional thing to check is the location and alignment of the holes in the receiver; if they are too low or out of alignment...

Things happen; anything can happen during the milling processes...

If the bolt fails to charge or reset the hammer far enough down to lock it; the bolt and hammer are too far apart or the bolt isn't going back far enough...

Unrelated but I had a spent primer sitting under my LR.308 seer , it was causing automatic firing ..so anything of the smallest magnitude can happen..

Thanks for posting! I've been around ARs since 1979, and still learning.