Gunsmithing AR trigger problem.

[Militarybuilt]

So I took out my newly built AR today for its initial flogging but I was quickly halted when the first 6 rounds went full auto. Upon closer inspection ipthe issue is when you let go of the trigger after firing the hammer misses catching the sear and fires again. And again. But it not happens when I let off slow, if I let off quick it's fine. Any suggestions? It's a spikes lower with some MMC maybe? Parts kit. Thanks.

 

[Rprecision]

Re: AR trigger problem.

Well, there are some folks that have to pay a hell of alot for that feature.

Sounds like a pretty obvious disconector problem.

 

[MikeeBooshay]

Re: AR trigger problem.

Yes, they do pay a lot for it.

It's about $250k fine and ten years I believe......

OK, now for some help. You likely DO have a disconnector problem. Your lower parts kit contains a trigger, hammer, and disconnector, with associated springs and pins. With a little inspection, you should be able to determine which is defective. Either the disconnector is wedged and not moving freely, see that alot, or not catching the aft side of the hammer correctly.

With the upper off, hold your hand over the hammer, pull the trigger and hold it. The hammer should drop, sounds like that is OK. STill holding the trigger back, move your hand on the hammer aft, like the bolt cycling. The hammer should catch on the disconnector. Most of the time, this happens.

Now, move your hand slightly away from the hammer, it should stay. Release the trigger, usually this is where the hammer slips off the disconnector and drops, before the sear catches it. That is why your rifle is doubling.

Replace the defective parts, and also check the safety for correct functioning. That should fix your problem.

I guess it might also be possible to assemble the thing such that the safety doesn't work either. But you'd hafta force it together that way.

I guess you know you should not take this thing out until it's fixed right?

 

[3oh8er]

Re: AR trigger problem.

When ever I do any trigger group work or check out a new gun, after preforming the empty gun safety check I do the following:

Load one round in the magazine, fire, if all is well;
Load two rounds in the magazine, fire the gun being sure to hold the trigger back during the cycle;
If the gun cycles correctly fire the second round;
Repeat this process until you have five or six rounds in the mag and you have confidence in the gun's reliability.
If anything goes wrong stop and correct the problem.
After correcting the problem retest using the above procedure until you are satisfied.

Then, lock and load, fire for effect.

 

[KTDLS7]

Re: AR trigger problem.

Err,
Problematic components are:
Disconnector spring problem (most likely) or defective disconnector (replace), though you could have a defective hammer.

When a parts kit is used, sometimes the incorrect spring is used.

Check for an existing, correct and/or correct installation of disconnector spring. The correct spring is not "straight", but is "larger" at one end. The large end is pressed and held captive in the trigger bar.

After you find the problem, follow the function checks described in the previous posts.

Let us know what you find.

Good Luck,

Kevin

 

[turbo54]

Re: AR trigger problem.

You've got the bolt holdopen spring swapped with the disconnect or spring.

 

[biner626]

Re: AR trigger problem.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ktdls7</div><div class="ubbcode-body">Check for an existing, correct and/or correct installation of disconnector spring. The correct spring is not "straight", but is "larger" at one end. The large end is pressed and held captive in the trigger bar.

Good Luck,

Kevin </div></div>
THIS is the most likely problem. Do the function checks and you'll know if its safe.

 

[Militarybuilt]

Re: AR trigger problem.

Well the disconnect or was fine as was the trigger. The hammer was the issue. I looked at the sear engagement area and it looked like half of it was worn or filed away just slightly. If I can get a good picture I'll post it. I threw a factory DPMS hammer in and it works fine now. Thanks for all the help though.