Ar15 Trigger reset failure help

[Dasa]

I have never had this failure before on an ar 15 but this week I have had two different rifles have intermittent failure for the trigger to reset. Both rifles had a larue 2 stage trigger that had only a couple hundred rounds through them. One was a bcm upper 9” with factory Hornady 110 loads while suppressed. The other was an Smith and Wesson 15-22 standard length with cci sv. In both rifles it cycled and ejected fine and loaded correctly. The trigger was simply dead and wouldn’t reset unless you ejected the round. I checked every time and round loaded into another magazine and fired. This happened a dozen times or so each rifle. Any helpful suggestions for correcting? I am thinking trigger springs but seems odd for larue on two different rifles.

[Alaskapopo]

I have only had stock type triggers work well in ARs in 22 long rifle. 9mm is also tough on triggers and you need to get triggers that can handle the bolt speed from a blowback


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[NOSHMJ]

Do you have adjustable gas bolcks on either gun?  Maybe undergassed and short stroking???

[Dasa]

No adjustable gas blocks on either the 300blk is a standard bcm built upper and the 15-22 is just the standard blowback. On the 300blk it was supersonic factory loads while suppressed (so if anything a little over gassed at the time). I will try swapping to mil spec instead of larue mbt to see if it fixes the issue.

[NOSHMJ]

good luck

[Screaminyz]

I’m not sure if you bought the Larue mbt’s new or not but I thought they included a heavy and medium spring in the package. I might be thinking of a different trigger but if they do I would make sure you are using the lighter of the two.


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[mpom]

Have you called up Larue? Might be a problem with that unit, am pretty sure they will replace it.

 

Mark

[JonWayne]

Does the hammer stay stuck on the rear hook on the disconnector or does it follow the bolt?

 

I’m thinking the disconnector is getting hung up. Check the springs and make sure the trigger and disconnector rotate freely on the trigger pin when removed from the lower. Two in a row seems really odd which is why I would pull the lower apart and look everything over. 

[outerlimits]

had this happen on the last stage of  a major...single shot AR.  couldn't figure it out on the 4 hr drive home.  next day went to clean the gun, split it in half and happen to look into the lower and staring me in the face was a spent primer that had lodged itself under the rear of the trigger.  bizarre.

[dekindy]

Watched an AR15 cleaning video where he referenced blown primers several times. That is the only reference I have ever seen until now. Must be a real thing.

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[AHI]

Start with a good complete cleaning. 22s are /can be very dirty. 300 BO suppressed is very dirty.