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Discussion Starter #1
I was curious if anyone here as experienced this issue.

Last week I replaced my trigger with the Timney SCAR trigger. I did a small amount of training with it and I did not seem to have any issues. Today I took it out to train. Slow walk, firing on 100yrd targets as you close and move. Rapid reloads to keep engaging the targets on the move.

Today, when I inserted the new magazine for a speed reload and released the slide it began to auto-fire. First three rounds (like a three round burst) and the next time five founds. This only happens during a speed reload when the weapon is shouldered and off safe. Now if I do a traditional reload with the safety on, it's not an issue.

Step by step to induce discharge...

1. shoot, shoot, shoot, click.​
2. rotate and chamber check​
3. mag release​
4. index new mag​
5. insert new mag​
6. tap new mag​
7. hit ping pong (chamber round)​
8. bang, bang, bang, bang like the weapon is on full auto or burst. Trigger was not pulled and support hand was traveling back to grip the upper.​

New trigger related possibly? Has anyone else had this happen before?
 

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Take the Timney out and put the stock trigger back in. Then send the trigger back to Timney to test.
 

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Discussion Starter #3
I figured. This is the third time I have sent this trigger in. First two times it would failure to fire with light strikes. I'm over Timney at this point. Thanks.
 

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Is the trigger impacting the grip screw by any chance?
 

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A word to the wise, if ANY weapon other than a NFA stamped and registered selective fire goes awry, STOP SHOOTING IMMEDIATELY! Get as much distance between you and it as humanly possible, render it un-shootable ASAP, then contact a qualified Gunsmith or Armorer. If you get noticed, there's no amount of explaining you could do that will stop the inevitable especially if you keep shooting and trying to troubleshoot the problem. Trust me on this, years ago at a range I frequented another shooter had his AR go auto on him. He clearly wasn't that bright, kept shooting thinking WOW this is cool and quickly garnered the attention of the RSO's who quickly made a phone call, the rest as they say is history. BSO SWAT arrived as did numerous news choppers and "Auto-Man" was on his way to a new home.
 

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Heres what I would do:

1. Unload weapon
2 Remove pistol grip
3 make sure hammer is cocked
4 with an unloaded weapon recreate the steps you labeled that induced the problem.

If the hammer falls without you pulling the trigger, then i would suspect a fautly trigger


And as SeaMac has pointed out if the trigger is faulty get it out and FAR away from the weapon asap!
 
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On this topic I would ask, are you absolutely positive the grip screw is NOT protruding beyond the groove in the trigger module/lower? If even a bit of thread is showing you need to check that the screw is NOT protruding beyond the groove. All kinds of "fun" stuff will occur if it does. If you have anything other than a stock grip it is highly probable the screw is too long. Timney, Geiselle and others provide a shorter screw than stock but this still might not be short enough if your grip isn't factory. On my 16s I started with a G then went to a Shooting Sight, I had already changed my grip to a Magpul MOE+ and filed the stock screw down below even the screw hole in the lower just to be sure. It only takes a few minutes to file with a good and clean mill cut file.

No, not that I can see. The drop in seems pretty clean
 
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Is the trigger impacting the grip screw by any chance?
I second this. Had similar issue with an adjustable AK trigger (no live rounds but easy to diagnosis with dry firing), the extra material (in the case of the scar the grip screw) will push the trigger forward decreasing the sear area of contact with the hammer hook. This leads to the sear barely holding on to the hammer and doesn't take much force to set it off (say the carrier slamming home). Before you swap it back out for stock, check out the grip screw and make sure it's not protruding. Then cock the hammer back and look under it at where the hammer hooks onto the sear to see if there's enough engagement there or whether it's just barely holding the hammer back. If it's the latter then you have a problem and I would follow the Timney instruction accordingly to correct the issue. I'm not familiar with Timney SCAR triggers but the basic idea is you want to introduce more angle to the front of the trigger so you get a more positive retention of the hammer hook. And you do that by dialing in the front adjustment screw (if it has one) or dialing back the back screw (if it has one).

Here's a pic if you still have no idea what I'm talking about:
 

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Discussion Starter #10 (Edited)
A word to the wise, if ANY weapon other than a NFA stamped and registered selective fire goes awry, STOP SHOOTING IMMEDIATELY! Get as much distance between you and it as humanly possible, render it un-shootable ASAP, then contact a qualified Gunsmith or Armorer. If you get noticed, there's no amount of explaining you could do that will stop the inevitable especially if you keep shooting and trying to troubleshoot the problem. Trust me on this, years ago at a range I frequented another shooter had his AR go auto on him. He clearly wasn't that bright, kept shooting thinking WOW this is cool and quickly garnered the attention of the RSO's who quickly made a phone call, the rest as they say is history. BSO SWAT arrived as did numerous news choppers and "Auto-Man" was on his way to a new home.
Yes I hear you and that's an interesting story for sure. I was actually shooting with local SWAT guys. I was covered in that regard. However when a weapon goes haywire its back in the case. For me it was a safety issue. I had to replicate it to make sure I was not crazy but at that point it went away.

I just disassembled it again. I've got the stock grip and the grip screw does not seem to be protruding. However, I have a Giselle trigger on standby so I dropped in that grip screw that is much shorter.

I appreciate all the advice from everyone here. At this point I am just sending back the Timney and I dropped in the Giselle tonight. I'll take it to the range tomorrow and see if there is any issues. If not.....problem solved. It was an odd sensation having that thing unexpectedly go full auto on chambering. I've shot my fair share of weapons over the years in the military and I've never had an issue like this from a trigger replacement.
 

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Were you shooting reloaded/remanufactured ammunition? I've seen this issue before on an AR15....it was due to the primers on remanufactured ammunition and not the weapon itself.
 

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Discussion Starter #12
Were you shooting reloaded/remanufactured ammunition? I've seen this issue before on an AR15....it was due to the primers on remanufactured ammunition and not the weapon itself.
No it was new NATO green tips. I've been shooting this ammo with the M4 for years, then the SCAR for a few months before switching the trigger without any issues.
 

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Have you tried playing around with the adjustments? It might just be due to the trigger being set too light or the adjustment screws not loctite.
 
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Have you tried playing around with the adjustments? It might just be due to the trigger being set too light or the adjustment screws not loctite.
I did not and you are probably right. I have had so many issues with that trigger from light strikes to failure to fire and now this.....I'm over it. I honestly feel its unreliable. I imagine the problem could be solved messing with the adjustments somehow.
 

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I did not and you are probably right. I have had so many issues with that trigger from light strikes to failure to fire and now this.....I'm over it. I honestly feel its unreliable. I imagine the problem could be solved messing with the adjustments somehow.
That's the biggest downside to having an adjustable trigger; you can easily "adjust" it beyond the functional safety perimeter of firearm. But once you take the time to tweak it, it can perform better than a nonadjustable trigger.
 

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Yes Sir, VERY not cool!

Here is an update. I had a second Timney on order for my a Tavor SAR. There is nothing to adjust. You pull a pin, stock trigger pack drops out and then you drop in the new trigger. I took it to the range and it was full auto, all the time. Not cool. Timney triggers are just bad news IMO.
 

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Give Shooting Sight a looking at, Art's trigger that I put in my 16s feels terrific then again I'm a freak for all things rubber coated -don't get me started- I only got to shoot it a few times before I had to throw in the towel but there was a profound difference between it and the GSS trigger I pulled out and sold here.
 
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If changing he trigger on a SCAR 16S or 17S I would only put in the Geissele Super SCAR trigger. I've never seen or heard a single complaint when using the Geissele trigger.
 
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