2011, Random inconsistent trigger pull

[Jolly]

Hi Everyone,

I have an all original STI Eagle 5" with a bushing.  Original except I sent it back to STI recently to fix a broken barrel lug (timing was off).  I suspect this might or might not have anything to do with my issue now but it is odd having not done this prior.  They machined the frame slightly and went from a #2 to a #3 lug.  If you do a timing check it still fails so I imagine its still off slightly.  Pistol has about 5K rounds through it prior and about 1K after and was running like a champ up until last months match.  Trigger is around 2.8Lbs. 

 

Example, I will be shooting a string of targets and maybe 1 trigger pull out of the batch will be much harder to pull than the others so I nose dive it.  Totally random and unpredictable.  Last match it did this twice in 7 stages. I broke the pistol down, cleaned and checked everything.  I have kept a round count vs occurrence since and it seems so far to be three times in 140 rounds, totally random.  I even backed out the trigger screw a little but it didn't make a difference in my last practice.  Its loctited in place so I'm not sure how that could be the issue anyway as it can't move. 

 

The issue causes misses and lost time in a match so its a little frustrating. 

 

Any ideas? 

[Gooldylocks]

Have you checked the trigger bow for cracks?

[Jolly]

Hi Gooldylocks,

I took the pistol down completely and went over it very carefully, all parts look fine.  Trigger bow is good, trigger as a whole glides just fine with no hang ups.  I'm stumped.  

I'm going to practice again with it on Thursday so I will get more data but wanted to know if anyone else had something similar to this.  Hard to fix an issue that doesn't show itself 99% of the time.

[broadus123]

Did you check the overtravel adjustment or just turn it a little ? I have seen them mis adjusted from the factory.

[Racinready300ex]

Confirm Magazine doesn't interfere with the trigger bow.

[racer-x]

3 hours ago, broadus123 said:

Did you check the overtravel adjustment or just turn it a little ? I have seen them mis adjusted from the factory.

+1

Not enough overtravel will present just like this.

 

You may also have got a tiny piece of grit in there that pushed it over the edge from just barely enough overtravel, to not always enough.

Try increasing OT by 1/2 -1 turn and see if that fixes it.

 

 

 

[Jolly]

Thanks guys, I'll check magazines this evening.  I have five I use in rotation and it doesn't seem to be magazine dependent but certainly worth the look.  I have noticed #4 is often in use when this happens but it has happened with others.  I increased OT by 1/2 turn and will check it with practice this evening. 

 

Gun is clean, it's like new after I broke it down to check all the parts so that wasn't it.  I had hoped it was. 

[jimbullet]

Is your grip safety deactivated or not? 

[427Cobra]

Send it back to STI

[Jolly]

The grip safety is stock, as is all the gun. 

 

I've fired about 250rds through it since the OT screw adjustment and it seems fine now.  I have a match this weekend so we will find out for sure.  All things being equal that little screw had to be the problem but I don't see how since its glued in place. 

If it keeps it up I might send it back but with being right in the middle of the season I am going to try everything first. 

[broadus123]

I have seen them adjusted incorrectly from the factory. I doubt you will have any more trouble.

[jimbullet]

one of our guys at the range reported somewhat similar to what you encountered. It appeared that he was gripping the gun too high that the grip safety was engaging every so slightly. So either deactivate or do some filing on the grip safety leg so it disengages even with a little tap to it.

 

 

[Jolly]

Great idea, that's a possibility.  I'll take a look at this this evening.