AR Trigger Reset enigma

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I had an Anderson lower parts kit do the same thing. Mine wasn’t stainless though. It only happened about 5-6 times when it was brand new. I figure it must have just had a burr or little lip somewhere that quickly corrected itself. No issues anymore though. How many rounds through yours?
 
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7mmsavage said:
I had an Anderson lower parts kit do the same thing. Mine wasn’t stainless though. It only happened about 5-6 times when it was brand new. I figure it must have just had a burr or little lip somewhere that quickly corrected itself. No issues anymore though. How many rounds through yours?
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I’ve got only about 30-40 rounds through it. I took it out again today after taking the LPK out, inserting it without any springs to ID potential friction points, and then adding the springs. Same deal... it worked fine when dry firing, but I inserted a mag, fired, cycled, and then had to manually reset the trigger. I took a second lower configured the same to ensure that the issue was in fact the lower parts kit in lower 1. Lower 2 had no reset issue and functioned perfectly. I am now 100% certain that the LPK from lower 1 is out of spec. I suppose that’s a good excuse to get a LaRue MBT!
 
giggitygiggity said:
I’ve got only about 30-40 rounds through it. I took it out again today after taking the LPK out, inserting it without any springs to ID potential friction points, and then adding the springs. Same deal... it worked fine when dry firing, but I inserted a mag, fired, cycled, and then had to manually reset the trigger. I took a second lower configured the same to ensure that the issue was in fact the lower parts kit in lower 1. Lower 2 had no reset issue and functioned perfectly. I am now 100% certain that the LPK from lower 1 is out of spec. I suppose that’s a good excuse to get a LaRue MBT!
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Have you tried dryfiring, cycle, keep your trigger depressed, then letting the bolt go forward again and trying the trigger?
 
Before you spend money on another LPK make sure your pin holes etc. Are where they are supposed to be.
 
LoonWulf said:
Have you tried dryfiring, cycle, keep your trigger depressed, then letting the bolt go forward again and trying the trigger?
Click to expand...

Yes, and that’s what is so odd. It works fine when I dry fire and manually cycle and it will occasionally work when there are one or two rounds in the mag, but nearly never works when there are more rounds in the mag.
 
Casefull said:
Before you spend money on another LPK make sure your pin holes etc. Are where they are supposed to be.
Click to expand...

Good point. He could swap trigger components in the lowers and see what happens. Time permitting replace one part at a time until the culprit is found.

That and keep shooting it. Only 30-40 rounds so far it may just work itself out like mine did. I’m a tinkerer so I’d be tempted to polish all of the trigger components then see what happens.
 
giggitygiggity said:
Yes, and that’s what is so odd. It works fine when I dry fire and manually cycle and it will occasionally work when there are one or two rounds in the mag, but nearly never works when there are more rounds in the mag.
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Interesting, sounds like your boots not coming back quite far enough to cock the hammer. I'm assuming it locks back fine on an empty mag.
 
The most common mistake on lower build is improperly installing the trigger spring and the result is a failure to reset the trigger. I am with Mistwolf on that one.
 
Wreck-n-Crew said:
The most common mistake on lower build is improperly installing the trigger spring and the result is a failure to reset the trigger. I am with Mistwolf on that one.
Click to expand...

Yes, it and all the springs are installed correctly. I even double checked before firing it last. I was hoping that it would have been a simple knucklehead mistake, but it wasn’t. I ordered a LaRue MBT-2S today as well as an oops kit so I can a) have a better and functioning trigger and b) cannuse the pops kit to further test/swap out individual components on the trigger in question.
 
LoonWulf said:
Interesting, sounds like your boots not coming back quite far enough to cock the hammer. I'm assuming it locks back fine on an empty mag.
Click to expand...

If the bolt weren’t coming back far enough, it wouldn’t reset at all. The bolt has to be coming back far enough to catch the disconnector if it’s able to be push-reset. There’s just something binding or otherwise out of spec which isn’t letting the trigger move forward to reset, transferring from the disconnector to the sear.

If the bolt isn’t traveling rearward enough to reset, meaning it’s not traveling enough to catch the disconnector, then pushing the trigger forward wouldn’t reset the trigger, it would simply be dead.
 
I have had this problem on several factory AR triggers. The hammer or disconnector hook probably has a burr or rough spot that is preventing the reset. Polishing the mating surfaces without changing any of the angles should fix it.
These days, I normally drop a CMC unit in and am good to go.
 
I have this problem on my Blackout after about 1000 rounds or lubed cast bullets without cleaning. Powder and lube residue build up in the lower and prevent the trigger from moving. Flooding it with lube is a temporary fix, a blast with carb cleaner a more long-lasting one.

What perplexes me is that it works when dry firing but not with rounds in the mag.

As others have said, try swapping parts with another rifle and see if the problems stays with the lower or transfer to the other gun.
 
Stacked tolerances.

More than one part OR the lower is at opposite ends of the min & max specifications.
 
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