Accidental bump fire issue

BoulderE89 · Aug 15, 2020

I’m not looking for advice on how I set up my rifle, just looking for solutions on how to fix the problem.

I recently took my 18” spr style AR and threw and adjustable gas block, light weight bcg, and lightweight buffer/reduced power spring. I got it cycling fine and locking the bolt back on the last round, but every once in a full 30 round mag I’ll pull the trigger and it’ll send 2 rounds consecutively with the one pull. Why is this happening and what do I need to do to correct it?

For reference I have a taccom reduced spring/light buffer setup, rubber armory light bcg, and an Odin works click adjustable gas block. Before adding these items on it ran flawless (with lots of extra gas) I also run this rifle with a nomad suppressor and trigger is a trigger tech adjustable trigger

whatsupdoc · Aug 15, 2020

Most likely cause is you are bump firing the rifle as it recoils. Do you grip it loose?

BoulderE89 · Aug 15, 2020

whatsupdoc said:
Most likely cause is you are bump firing the rifle as it recoils. Do you grip it loose?

Mahbe! I had a pretty solid prone position built up so I would be surprised if it was that but don’t think I can rule it out either

308pirate · Aug 15, 2020

BoulderE89 said:
I’m not looking for advice on how I set up my rifle, just looking for solutions on how to fix the problem.

I recently took my 18” spr style AR and threw and adjustable gas block, light weight bcg, and lightweight buffer/reduced power spring. I got it cycling fine and locking the bolt back on the last round, but every once in a full 30 round mag I’ll pull the trigger and it’ll send 2 rounds consecutively with the one pull. Why is this happening and what do I need to do to correct it?

For reference I have a taccom reduced spring/light buffer setup, rubber armory light bcg, and an Odin works click adjustable gas block. Before adding these items on it ran flawless (with lots of extra gas) I also run this rifle with a nomad suppressor and trigger is a trigger tech adjustable trigger

Was it like this?

BullGear · Aug 16, 2020

Please remove this thread. You've just admitted that your firearm can be considered a machine gun. I know it sounds stupid and makes no sense, but there have been instances where the men in black show up. Many ROs will politely ask you to put the firearm away or leave the range. This is not a joke.

Reverie Ranges · Aug 16, 2020

I had the same problem a while back and the second round fired was not extracting (empty case in chamber). I did some trigger polishing to re-establish the hammer catch to the correct position and that corrected the issue.

soap11x · Aug 16, 2020

Have seen this on worn-out M4's. Trigger and hammer pins were worn out. One shot went off on the pull, and on the release. Pay attention if this is the issue. If so, replace said pins and invest in anti-rotation/walk pins.

ormandj · Aug 16, 2020

soap11x said:
Have seen this on worn-out M4's. Trigger and hammer pins were worn out. One shot went off on the pull, and on the release. Pay attention if this is the issue. If so, replace said pins and invest in anti-rotation/walk pins.

If it’s a TT and installed correctly it will tension pins even if they are a little bit worn. The trigger may be set very light and recoil is leading to bump fires due to bad rifle and recoil control. OP, adjust trigger up to 4 lbs and make sure it’s tensioned properly. Make sure to shoot with a firm shoulder and cheek weld as well as hold.

jcmullis2 · Aug 16, 2020

I’ve seen a friends do it and assumed it was because he rarely cleaned it. When he did he didn’t do a good job. He thought hosing it down with a WD40 was cleaning it. I was afraid the damn thing was gonna discharge before a round was fully chambered and blow up. I would Damn sure tear it down and check all the fire control parts at a minimum. If that doesn’t help take it to a good smith so at least you’ll have proof of the problem and that you thought it had been repaired. If someone reports you for having a automatic rifle you’ll want to have something proving you had done everything possible to remedy the problem. Otherwise you’ll be standing there with your bare face hanging out trying to convince a judge that you aren’t responsible. Not easy to do when you knew of the problem and didn’t fix it. Just saying

hlee · Aug 16, 2020

Light weight trigger and poor trigger form will cause this in a large frame gasser. Lots of people try to jump off of the trigger when the gun fires, instead of pinning the trigger to the rear through recoil. On a light weight trigger, this can cause a bump fire- especially in a rifle with actual recoil. I saw a guy do this for several stages at a club match about a year ago. He went to single loading to resolve the issue. Haven’t seen him since. If you haven’t monkey-fucked the trigger, it is probably how you are (not) following through once the trigger breaks.

supercorndogs · Aug 16, 2020

I don't think pinning the trigger back against the overtravel stop is correct either. If you are hitting the hard stop at the end of the triggers overtravel you are effecting the rifle with your trigger pull. Pulling too hard and pinning it against the overtravel stop, is the flip side of the coin from slapping the trigger, and not having good follow through.

hlee · Aug 16, 2020

supercorndogs said:
I don't think pinning the trigger back against the overtravel stop is correct either. If you are hitting the hard stop at the end of the triggers overtravel you are effecting the rifle with your trigger pull. Pulling too hard and pinning it against the overtravel stop, is the flip side of the coin from slapping the trigger, and not having good follow through.

I’ll just leave this here...

supercorndogs · Aug 16, 2020

supercorndogs said:
I don't think pinning the trigger back against the overtravel stop is correct either. If you are hitting the hard stop at the end of the triggers overtravel you are effecting the rifle with your trigger pull. Pulling too hard and pinning it against the overtravel stop, is the flip side of the coin from slapping the trigger, and not having good follow through.

@lowlight Is this something I am misunderstanding?

BoulderE89 · Aug 16, 2020

308pirate said:
Was it like this?

Yeah exactly like that...I guess it was bump fire. Although it wasn’t nearly as bad as in that video, it’s the same idea.
So help me understand, cause in my mind the lighter recoil should make this less likely to happen. What’s a good way mechanically to prevent it from happening? Do I need to increase the recoil again? Or just increase the trigger pull weight? (Currently set around 2.5 pounds)
im sure people will tell me to hold it better or something but I’m not convinced that’s why cause none of my other rifles have ever done that. And this rifle, which I’ve shot for years, never did that until I put these new components in. I’ve had the trigger most of this year with no issues to speak of either

theLBC · Aug 16, 2020

yeah, school of thought on trigger control is never press past the break, but that is different on a gas gun because the machine is still running after the break, unlike a bolt or lever action where nothing else happens except the bullet going out.

david walter · Aug 16, 2020

I had that happen and it was because of a blown primer that was stuck under the trigger just enough to make the gun fire again under recoil as long as I was pressing the trigger.

remove and reinstall the trigger. The piece causing me grief as very small. I didn’t see it until it fell on the white paper I put on my bench after someone told me to look for it.

also, no “men in black” came, and I was shooting at a public range. That’s absurd.

shoot4fun · Aug 16, 2020

david walter said:
I had that happen and it was because of a blown primer that was stuck under the trigger just enough to make the gun fire again under recoil as long as I was pressing the trigger.

remove and reinstall the trigger. The piece causing me grief as very small. I didn’t see it until it fell on the white paper I put on my bench after someone told me to look for it.

also, no “men in black” came, and I was shooting at a public range. That’s absurd.

Had this happen to me once but it could not be described as a bump-fire. The shots were not a double and, per the RO running the stage, my finger was not on the trigger when the 2nd shot went off.
There was one certain "big-name" trigger that the company I worked for installed in one particular model AR that caused bump-fire by several shooters on several occasions (two-stage). A minor change by the supplier seemed to correct the issue (spring weight IIRC).

whatsupdoc · Aug 16, 2020

Ok lets look at this, as the rifle fires the first rearward impulse is from the round going off. The rearward movement from the round firing stops then the bolt carrier travels rearward and stops causing another separate impulse. The carrier then moves forward until it again stops causing another impulse.

What seems to be happening here barring some mechanical issue is you are disconnecting from the rifle somewhere in the firing sequence and as the rifle moves forward your trigger is striking your finger causing the double fire.

Put a heavy mil trigger and it will go away or put a 1.5 lb trigger in it and it will magnify your error.

308pirate · Aug 16, 2020

BullGear said:
Please remove this thread. You've just admitted that your firearm can be considered a machine gun. I know it sounds stupid and makes no sense, but there have been instances where the men in black show up. Many ROs will politely ask you to put the firearm away or leave the range. This is not a joke.

It's a bumpfire. Nobody from any government agency is going to show up. Your post is a joke.

BullGear · Aug 16, 2020

308pirate said:
It's a bumpfire. Nobody from any government agency is going to show up. Your post is a joke.

One pull of the trigger resulting in multiple shots fired is not a bumpfire, it's a violation of NFA laws. You're the joke if you don't know the laws. A bumpfire does in fact have the trigger pulled for every shot fired.

308pirate · Aug 16, 2020

BullGear said:
One pull of the trigger resulting in multiple shots fired is not a bumpfire, it's a violation of NFA laws. You're the joke if you don't know the laws. A bumpfire does in fact have the trigger pulled for every shot fired.

What the OP thinks happened and what actually happened are two different things. 99.9999999% of the time someone thinks their rifle or pistol "went full auto" they just bumped the trigger without noticing.

Bumpfires with very light triggers will sound exactly like full auto. See the video I posted.

theLBC · Aug 16, 2020

BullGear said:
One pull of the trigger resulting in multiple shots fired is not a bumpfire, it's a violation of NFA laws. You're the joke if you don't know the laws. A bumpfire does in fact have the trigger pulled for every shot fired.

i think the trigger "pulled" and "actuated" may be the same thing here.
while the shooter may not be "pulling", his finger is still "actuating" the trigger as the firing group moves back and forth independently from his finger.

Downtown · Aug 16, 2020

It could quite likely be a legitimate bumpfire. I installed a light Giessle trigger with a very short reset in a 3-Gun AR and found that when I ran it really fast, it would seem to double. Upon careful examination, it turned out to be a bumpfire. Man, that trigger had a really short reset. Perfect for 3-Gun.

hlee · Aug 16, 2020

theLBC said:
i think the trigger "pulled" and "actuated" may be the same thing here.
while the shooter may not be "pulling", his finger is still "actuating" the trigger as the firing group moves back and forth independently from his finger.

You mean, a, bump fire?

theLBC · Aug 16, 2020

hlee said:
You mean, a, bump fire?

yes.

whatsupdoc · Aug 16, 2020

Another thing about this BS full auto twist, although not impossible it would very difficult for an ar15 to fire multiple rounds with one trigger pull.
Even if the disconnector failed and the hammer was not caught and held by the disconnector the hammer would ride the "slow" bolt carrier back into battery and would not have enough energy to ignite the primer.

Now back to our regularly scheduled program.

OP one thing you should keep in mind, make sure you "feel the trigger reset" after you fire a round. So you squeeze the trigger and hold, then you consciously release the trigger and hear/feel it "click" reset for the next shot.

BoulderE89 · Aug 16, 2020

Ya I’m gonna go back and shoot it next weekend. I’m 98% positive I had the gun under control (in the prone, taking individual and deliberate shots at 500 yards, with lots of contact between me and the rifle) I figured the lightweight components were to blame but I’ll do prone shots and pay attention to my trigger control more.

BullGear · Aug 16, 2020

BoulderE89 said:
Ya I’m gonna go back and shoot it next weekend. I’m 98% positive I had the gun under control (in the prone, taking individual and deliberate shots at 500 yards, with lots of contact between me and the rifle) I figured the lightweight components were to blame but I’ll do prone shots and pay attention to my trigger control more.

So for those who couldn't read the words from your first post, you are pretty sure you pulled the trigger 1 time and the rifle fired 2 rounds?

Just checking?????

BoulderE89 · Aug 16, 2020

Well I thought I did, but people seem to think it’s me bump firing so I’m gonna check. I don’t think it’s the trigger since my trigger tech has been flawless up till now. I added the new components for lighter recoil and assumed they were the problem. But it may be me, idk

supercorndogs · Aug 16, 2020

hlee said:
I’ll just leave this here...

Beyond Trigger Control: The Imperceivable Press

Follow Sniper's Hide and pick up the latest information on all things precision rifle related. Sniper's Hide Training is for the serious tactical marksman.

www.snipershide.com

The Freeze is where Followthrough begins. Followthrough is the “Forgotten Fundamental” because it is often neglected by the shooter. Some triggers have a noticeable travel behind the break and some do not. Regardless, one must FREEZE at the break of the trigger and not exert any unwanted rear pressure beyond the trigger’s break.

Here you go. Follow through is not pinning the trigger against overtravel stop. Kind of like overloading the bipod, this is a very misunderstood part of fundamentals.

Milo 2.5 · Aug 16, 2020

BoulderE89 said:
I’m not looking for advice on how I set up my rifle, just looking for solutions on how to fix the problem.

I recently took my 18” spr style AR and threw and adjustable gas block, light weight bcg, and lightweight buffer/reduced power spring. I got it cycling fine and locking the bolt back on the last round, but every once in a full 30 round mag I’ll pull the trigger and it’ll send 2 rounds consecutively with the one pull. Why is this happening and what do I need to do to correct it?

For reference I have a taccom reduced spring/light buffer setup, rubber armory light bcg, and an Odin works click adjustable gas block. Before adding these items on it ran flawless (with lots of extra gas) I also run this rifle with a nomad suppressor and trigger is a trigger tech adjustable trigger

Pay attention to if it happens on the trigger reset, fire pulling, then when letting off. I had this happen on a trigger replacement, smith said it was something to with the safety. He fixed it and i didn't really care at the time.
The vid of the pcc going wild, that is too light of a buffer system, or anyway that is what my JP GMR 15 was doing, 2-3 rd bursts were plain fun, 5 rds with one pull opened ones eyes.

supercorndogs · Aug 17, 2020

My dad had an RRA 2 stage bumping off on him. Part off the trigger was rubbing on the safety inside the lower. I the lever had material that needed to be filed away to give the trigger some clearance. Pull your lower off and see if the trigger is rubbing on the safety on the inside.

BoulderE89 · Aug 17, 2020

Milo 2.5 said:
Pay attention to if it happens on the trigger reset, fire pulling, then when letting off. I had this happen on a trigger replacement, smith said it was something to with the safety. He fixed it and i didn't really care at the time.
The vid of the pcc going wild, that is too light of a buffer system, or anyway that is what my JP GMR 15 was doing, 2-3 rd bursts were plain fun, 5 rds with one pull opened ones eyes.

That’s a good point, now that you mention it I had to retighten the screw of my ambi safety selector when I got home. Idk if that affected it but if it let it wiggle loose enough to mess with the trigger then that could be it

hlee · Aug 17, 2020

supercorndogs said:
Beyond Trigger Control: The Imperceivable Press

Follow Sniper's Hide and pick up the latest information on all things precision rifle related. Sniper's Hide Training is for the serious tactical marksman.

www.snipershide.com

Some triggers have a noticeable travel behind the break and some do not. Regardless, one must FREEZE at the break of the trigger and not exert any unwanted rear pressure beyond the trigger’s break.

Here you go. Follow through is not pinning the trigger against overtravel stop. Kind of like overloading the bipod, this is a very misunderstood part of fundamentals.

Here you go, depends on the trigger... I think we’re in violent agreement. Freeze, don’t let the trigger move. Maybe ”pin to the rear” is excessively worded but you’re not jumping off of it like you’re trying to send singles out of a full auto.

I don’t have any triggers that I can stop the movement on before they hit the stop. Not sure I’d like a trigger that felt like I was dangling in space instead of a crisp break and immediate stop. Mil spec ar15, giesele ssa-e, sd-e, rock river national match- they all break and stop (3.5 to 4lb total pull weight). Very minimal over travel. They’re not stopping before they hit the wall. Remington 700 factory (30 years old, 2 lb single stage), timney rpr trigger (2lb total), Kidd 10/22 2 stage (2lb total weight). They break and stop too. Trying not to hit the overtravel stop with a Calvin elite is a great way to double a large frame gasser. Never shot one but watched a guy double his way out of a match. Even the tapco 2 stage in my ak breaks and stops. Not crushing the triggers, but that 2-4lbs required to break them sends them the limit of travel.

What triggers have so much overtravel that the force required to break them doesn’t send you to the limit of travel? Genuinely curious.

supercorndogs · Aug 17, 2020

I shoot Timney 510, 40x, Trigger tech Primary, Huber, Gieseille super 700, 1911's, CZ75, SP01, P-09, Ruger MKIII, GRT-III, 10/22, and RRA NM without pinning the triggers against the stop. I don't know what to tell you. I think you misunderstood the video you posted and now you are doubling down for no reason.

hlee · Aug 17, 2020

Not too proud to admit I’m wrong. Just pulled out the rpr that I haven’t shot in at least a year and, yes there is a lot of overtravel in that trigger. There is probably a mm or more travel between the break and the overtravel stop. That is not the case, however, with the AR triggers that I have on hand.

Powder_Burns · Aug 17, 2020

I’ve bump fired my 5.56 with a mil-spec trigger group before, but my .308 and my .458S have 2-stage triggers and have never been bumped. Go figure, the 6lb trigger in the lightest recoiling semi-auto I have has done it, but my heavier recoiling rifles with 2-stage don’t. Follow through is a thing.

AMGtuned · Aug 17, 2020

A buddy brought his first build out shooting once. A 16", 6.5grendel, with lots of BCM parts. He built the lower himself. First few shots were DEFINITELY of a faster nature. After inspection, it WAS firing 2 and 3 shots per pull, and it was because of his lack of a disconnecter spring. So, my thought is a broken, or missing disconnecter spring WILL cause multiple discharges. Simply because the hammer is left without control, and flying around with the BCG. Be safe, and get her fixed

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