Suppressor causing my AR to fire bursts and fail to reset

[okie]

If you are sure it’s not bump firing then it it something wrong with the trigger, dirty to the point of obstructing disconnector movement, broken hammer pin, disconnector spring installed the wrong way, disconnector spring binding, burr or excessive wear on a sear surface...



Bump fire means the rifle is bouncing forward enough after recoil that the trigger runs into your trigger finger and fires.

To troubleshoot for this you need to pull the trigger pretty hard and consciously keep it pulled all the way to the rear through recoil.

I could see it kind of sort of being that bump fire is maybe PART of the problem. My guess is that the hammer is often being caught not fully engaged with the sear surface and that a slight breeze could pull the trigger at that point.

Bump fire in my mind also doesn't really offer much explanation for the failure to reset, which is probably about every five rounds now. The issue began as occasional bursts, which became frequent, then the bursts began giving way to failures to reset, which are now the dominant problem.

In fact, with 5.56, failure to reset is now the only problem. I have not been able to get 5.56 to fire a burst like with 223.

I'm also not satisfied that bump fire could produce the rate of fire this thing is putting out, or the regular rate of fire. Bump fire, even when intentional, has that characteristic variable rate of fire. This is an extremely fast rate of fire, and has a very regular cadence.

I can get the rifle to bump fire if I hold it loosely and don't use the stock, but it has that characteristic variable rate of fire, and is slower than the random bursts I experience.

So it's really following the pattern of a worn out trigger that's extremely typical. Bursts that grow in frequency and duration, that eventually give way to only failures to reset within a few hundred rounds. Issue is, this trigger is practically brand new.

It's a mystery to me, so it's going back to the manufacturer, and it will be replaced with a milspec trigger that I've already ordered. I have one, or several lol, in my parts bins somewhere but finding it/them would be a major headache at this point, so I just ordered a new Colt trigger from Armsunlimited. Not looking forward to the grittiness, but I'm 99.9999% positive it's going to solve the issue and return my gun to its former glory.

[Todd.K]

Bump fire in my mind also doesn't really offer much explanation for the failure to reset

Hammer down but hasn’t fired? If the timing is off the hammer drops before the bolt is in battery or just follows it forward. Could be from a disconnector problem or bump fire, though it happens more from the disconnector failure in my experience.

Does it pass a function check?

Bump fire with a light+short reset match type trigger is often faster and more consistent than what you are used to with a more military style trigger.

[okie]

Hammer down but hasn’t fired? If the timing is off the hammer drops before the bolt is in battery or just follows it forward. Could be from a disconnector problem or bump fire, though it happens more from the disconnector failure in my experience.

Does it pass a function check?

Bump fire with a light+short reset match type trigger is often faster and more consistent than what you are used to with a more military style trigger.

Seems like a really unlikely thing to happen like five times a mag. The timing would have to be absolutely perfect.

And my understanding of bump fire is that the inertia of the bolt going home drives the gun into the trigger finger, so it seems like by definition the bolt would have to be in battery to cause the bump fire? In which case I shouldn't be getting hammer follow?

[tweakmeister]

I also saw this happen with a Brownells B-GRF and assume an S3G would do the same. The trigger reset fine unsuppressed and when the upper was removed (hand cycling the trigger).

Geissele said there are too many variables to warrant replacing it and that if it worked fine hand cycling then it should be okay. The engagement surfaces looked fine.

The weapon would occasionally burst while suppressed and continue going with the finger off the trigger then stop after a handful of rounds. The rate of fire was extremely high. Would love to see if there is a pattern here that would indicate how to repair it (heavier buffer?). Ultimately in this case the trigger was cheap enough that it was disposed to avoid further headaches.

[MistWolf]

You see that spring in the photo, just above the G and the E? Remove it and install a new replacement.

[tweakmeister]

Thank you for the info. Is there an "enhanced" version of this spring sold by any manufacturer? What is the usual service life of this spring?

It looks like Geissele sells a replacement spring kit.

[Uncas47]

I could see it kind of sort of being that bump fire is maybe PART of the problem. My guess is that the hammer is often being caught not fully engaged with the sear surface and that a slight breeze could pull the trigger at that point.

Bump fire in my mind also doesn't really offer much explanation for the failure to reset, which is probably about every five rounds now. The issue began as occasional bursts, which became frequent, then the bursts began giving way to failures to reset, which are now the dominant problem.

In fact, with 5.56, failure to reset is now the only problem. I have not been able to get 5.56 to fire a burst like with 223.

I'm also not satisfied that bump fire could produce the rate of fire this thing is putting out, or the regular rate of fire. Bump fire, even when intentional, has that characteristic variable rate of fire. This is an extremely fast rate of fire, and has a very regular cadence.

I can get the rifle to bump fire if I hold it loosely and don't use the stock, but it has that characteristic variable rate of fire, and is slower than the random bursts I experience.

So it's really following the pattern of a worn out trigger that's extremely typical. Bursts that grow in frequency and duration, that eventually give way to only failures to reset within a few hundred rounds. Issue is, this trigger is practically brand new.

It's a mystery to me, so it's going back to the manufacturer, and it will be replaced with a milspec trigger that I've already ordered. I have one, or several lol, in my parts bins somewhere but finding it/them would be a major headache at this point, so I just ordered a new Colt trigger from Armsunlimited. Not looking forward to the grittiness, but I'm 99.9999% positive it's going to solve the issue and return my gun to its former glory.

Okie, I have Colt FCGs in all my Colts, sharp letoff, no creep, fast strong reset, no grit. I've got two SSAs, don't like them, don't use them, don't care.

[okie]

I also saw this happen with a Brownells B-GRF and assume an S3G would do the same. The trigger reset fine unsuppressed and when the upper was removed (hand cycling the trigger).

Geissele said there are too many variables to warrant replacing it and that if it worked fine hand cycling then it should be okay. The engagement surfaces looked fine.

The weapon would occasionally burst while suppressed and continue going with the finger off the trigger then stop after a handful of rounds. The rate of fire was extremely high. Would love to see if there is a pattern here that would indicate how to repair it (heavier buffer?). Ultimately in this case the trigger was cheap enough that it was disposed to avoid further headaches.

Yep, same here. Like all the brass from a four round burst will land at approximately the same time. I'm estimating a good 900 rpm, which is the normal cyclic rate for an SBR.

I already tried using an H3 buffer and it didn't help.

[Todd.K]

And my understanding of bump fire is that the inertia of the bolt going home drives the gun into the trigger finger, so it seems like by definition the bolt would have to be in battery to cause the bump fire? In which case I shouldn't be getting hammer follow?

The rifle can bounce off your shoulder or a bipod as well. I believe it’s more likely with the recoil impulse of a suppressed rifle. Loading up the legs of a bipod while holding the rifle loosely works quite consistently.

[okie]

The rifle can bounce off your shoulder or a bipod as well. I believe it’s more likely with the recoil impulse of a suppressed rifle. Loading up the legs of a bipod while holding the rifle loosely works quite consistently.

The silencer actually reduces the felt recoil by a lot. I think it's the faster bolt with the silencer that's exacerbating the issue, not the felt recoil.