My Gun Went Off, No Trigger Pull!!!

[MarcSpaz]

Hey folks. For the first time ever, I had a gun fire while chambering a round. I was working on zeroing my new scope, I put a fresh magazine in, hit the bolt release, and when it hit, the rifle fired! It scared the hell out of me!

Please, please, please, always make sure when you are handling a weapon, its pointed in a safe direction. I was lucky and the rifle was pointed down range due to good habits, but it could have just as easily killed someone.

I know it very rarely happens, but it happens. Be safe.

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[Snakester]

I had it happen several years ago with a 20 ga. 870 Rem. I was shooting Skeet and had the Shotgun pointing straight up. When I chambered a shell it went off....Scared all 3 of us !

[MarcSpaz]

Man... That's a bad situation to Randy. I hope you guys took a few step with the Earths rotation just to be sure that shot didn't come back down. Seems impossible, but with wind and Earth rotation, I wouldn't be surprised.

Its funny, at a range with weapons being fired all around, you wouldn't think it wouldn't spook you. It sure as heck got me to flinch.

[FiremanBob]

What kind of rifle, and have you diagnosed why it happened?

[Palladin]

^This^

And do you have the fired casing? I'd like to see that primer... it might give you a clue to what happened

[Palladin]

New scope = the .308?

[MarcSpaz]

It was on my SIG 716 (7.62/.308). The case flew into a big pile of brass on the floor. There is no way I was finding the right one.

I recently installed a new Geissele SSA-E trigger group. The trigger was not set after the discharge. These are not adjustable triggers (just drop-in), so there is not much to look at. If I was going to guess, I would say the hammer hook was latched, but slipped off the sear from the impact as the bolt seated. I say that because, if the hammer never latched, there would not have been enough pressure to fire as the hammer followed that bolt assembly forward.

The last time I went to the range, I noticed I had a few bump fires. I thought it was from not properly following through on the trigger pull correctly. Now I am starting to think otherwise.

I didn't have any double fires (bump fires) today, but I am going to be paying very, very close attention to this rifle over the next few uses. I may even put it in a vice at the range, point it down range and try some shock tests with a rubber mallet (with no rounds in it, of course).

[Rumson]

I had a pistol incident several years ago with my XD40. I was amped up doing drills and was literally slamming the palm of my hand on my magazine base during insertion of it. The slide went forward from the mag slap and boom. The pistol was pointed down range. I was able to reproduce it again with another very aggressive magazine load.

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[M1A4ME]

I'd agree about the hammer following the bolt forward usually not (never in my experience) setting the round off.

I'm seen it with an M1A and an AR15 and with both it was just a "dead" trigger when it happened. Pull the bolt back, eject the round in the chamber and let it go forward and it would fire that next round, but then you'd have the dead trigger again after that one round fired.

I had an AR15 "go off" on my one day but I'd blown a primer out of a case and it was back in the trigger works binding stuff up. It wouldn't fire, I'd pulled the trigger, no bang, made sure it wasn't on safe, pulled the trigger again, no bang. Dropped the rifle off my shoulder with it pointing down range, turned my head to tell my brother something was wrong and it went bang. Had to take it apart and then I could see the primer down inside.

[RO73]

Check with Geissele. I have geisseles on all my ARs, but I know that they don't recommend them for certain guns. Depending on the bolt, the SSAE may not be compatible.

[AppleaDay]

I've had hang fires but never a slam fire <knocks wood>
Glad nobody got hurt

[Palladin]

With your description of bump fires, my curiosity's piqued.

If the carrier group is the same as a -15, there's enough mass in the firing pin to set off a round when the bolt slams home... if it's not restrained properly.
Next time you shoot it, set up with a brass catcher or tarp and drop the bolt on a bunch of rounds. Check the rounds (or the empties if it goes off again) for light strikes on the primer.
I've seen this on an AR15 before, and it's disconcerting to say the least.

[MarcSpaz]

Good idea. I will do that test for sure.

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[Reverenddel]

This is all good information! Appreciate you putting this online. Thanks!

[0ne5hot]

If the carrier group is the same as a -15, there's enough mass in the firing pin to set off a round when the bolt slams home...for light strikes on the primer.
I've seen this on an AR15 before, and it's disconcerting to say the least.

I have noticed alot of light strikes on primers in my AR pattern rifles when the bolt is dropped but I have never had one cook off yet. The only things I can think of to address this issue is to get a titanium firing pin, which is lighter then the standard steel ones or don't use the bolt release, but then you could have issues with the bolt not seating completly, but all mil-spec ARs have the correct tool to fix that issue.

[grumpyMSG]

If the carrier group is the same as a -15, there's enough mass in the firing pin to set off a round when the bolt slams home...for light strikes on the primer.
I've seen this on an AR15 before, and it's disconcerting to say the least.

I have noticed alot of light strikes on primers in my AR pattern rifles when the bolt is dropped but I have never had one cook off yet. The only things I can think of to address this issue is to get a titanium firing pin, which is lighter then the standard steel ones or don't use the bolt release, but then you could have issues with the bolt not seating completly, but all mil-spec ARs have the correct tool to fix that issue.

There is so much bad information being spread about the AR family of weapons at this point by so called experts. The bad part is, if you are relatively new to the platform and a don't have a mechanical aptitude, you won't be able to tell who knows what they are talking about and who doesn't.

1. ARs have been "Marking" primers for the whole time they have been in existence. It is not going to affect anything. If you kept the same round and chambered and unchambered it hundreds or thousands of times, it might cause a problem, but odds are you are not going to be doing that.
2. The rifle should not fire when the rifle's bolt slams home from the mass of the firing pin. If it did the rifle would fire every time it cycled until the magazine was empty. The whole titanium firing pin versus steel is just a gimmick, if it affects anything it will be the length of time from you pulling the trigger and when the round goes off, milliseconds to be exact.
3. The term "cook off" is used in reference to a rifle or machine gun that has been fired a lot, the barrel and chamber are hot and when a round is chambered into the weapon, the residual heat in the chamber area causes the powder in the round to ignite, not the primer being struck. That is why most machine guns are open bolt weapons, the bolt and rounds stay to the rear until the trigger is pulled, the bolt slides forward chambers a round and fires it when it is fully locked. When you let go of the trigger the bolt stays to the rear. The main exception to that rule that are still in common use are the Browning designs.

All that said, your rifle should not have discharged when you chambered around. For starters, it sounds like you were messing with the rifle/scope and had the bolt locked to the rear, but did not have the selector set on safe. You said you recently installed a Giessele trigger, did yours come with replacement pins? If it did come with the replacement pins, did you install the new tighter tolerance pins with it or were you using your rifle's original pins? You mentioned the rifle bump firing. It sounds like your rifle in it's current condition could possibly fail a functions check.

ENSURE THE RIFLE IS UNLOADED, WHEN YOU PERFORM A FUNCTIONS CHECK!! With the weapon pointed in a safe direction, place the selector lever on safe. If it won't go, ensure the magazine is removed. Lock the bolt to the rear, place the selector lever on safe and ensure the chamber is empty. Release the bolt. Attempt to pull the trigger, the hammer should not fall. Place the weapon on fire. Squeeze and hold the trigger. The hammer should fall, remember that sound. While still holding the trigger, pull the charging handle all the way to the rear and release it. Slowly release the trigger, I emphasize SLOWLY, you should hear a small clunk as the hammer drops from the hook on the disconnector to the hook on the hammer. YOU SHOULD NOT HEAR THE HAMMER FALL, like you heard earlier. Now squeeze and hold the trigger and the hammer should fall. Do the squeeze, hold, charge the weapon, slow release cycle at least five times, preferably 10. The hammer should never fall during the slow release. If it does fall during the slow release, contact Giessele immediately about what needs to be done to remedy the situation. They have a stellar reputation and should be able to help you quickly.

[MarcSpaz]

So, I left an important part of the story out because it didn't seem relevant to the "please be safe" topic, but I will share them now.

My rifle has an adjustable gas block. I turned the auto-loading system off. When you do this, you use the rifle like a bolt action gun. You fire a shot, charge it. Fire a shot, charge it. I used the rifle in this mode so I could get less recoil and have better luck zeroing the rifle.

I fired 200 rounds using this method that day. I hit the bolt release 40 times. After manually pulling and releasing the bolt 240 times in one day, I only had one occurrence where the weapon discharged on its own.

The reason I know the hammer came off the sear is because after the round went off, I visually inspected the bolt, saw that it was fully locked, aimed down range and tried to pull the trigger, but nothing moved. I figured the hammer was was already forward because I had a dead trigger. I pulled the mag, popped the rear take-down pin and hinged it up. I visually confirm the hammer did indeed slip off the sear and it was all the way forward. I inspected all the parts to make sure nothing was loose, did a few dry charges and fires, everything seemed okay, so I went back to my "bolt action like" shooting.

All that said, your rifle should not have discharged when you chambered around. For starters, it sounds like you were messing with the rifle/scope and had the bolt locked to the rear, but did not have the selector set on safe.

You are correct.... sort of. The safety was not engaged, but I wasn't "messing" with the scope with the bolt open and a mag in it. That is a very bad idea. The scope has tactical turrets. I would fire a five round group, inspect the group, turn the dial, pull the charging handle and let the bolt catch do it thing, insert a fresh mag, aim down range, hit the bolt release, fire five more rounds.

You cannot engage the safety between rounds when manually cycling the rifle. I also don't normally put the safety switch on during mag swaps because I wouldn't do that in a live fire situation. I am not trying to build habits that will increase my response time if I am ever in a gun fight with my battle rifle. (God willing, that will never happen. Something has gone horribly wrong in the world if I'm in a gun fight.)

You said you recently installed a Giessele trigger, did yours come with replacement pins? If it did come with the replacement pins, did you install the new tighter tolerance pins with it or were you using your rifle's original pins?

It did come with replacement pins and they are installed. Yes, they were very snug compared to the mil-spec pins I pulled out.

You mentioned the rifle bump firing. It sounds like your rifle in it's current condition could possibly fail a functions check.

ENSURE THE RIFLE IS UNLOADED, WHEN YOU PERFORM A FUNCTIONS CHECK!! With the weapon pointed in a safe direction, place the selector lever on safe. If it won't go, ensure the magazine is removed. Lock the bolt to the rear, place the selector lever on safe and ensure the chamber is empty. Release the bolt. Attempt to pull the trigger, the hammer should not fall. Place the weapon on fire. Squeeze and hold the trigger. The hammer should fall, remember that sound. While still holding the trigger, pull the charging handle all the way to the rear and release it. Slowly release the trigger, I emphasize SLOWLY, you should hear a small clunk as the hammer drops from the hook on the disconnector to the hook on the hammer. YOU SHOULD NOT HEAR THE HAMMER FALL, like you heard earlier. Now squeeze and hold the trigger and the hammer should fall. Do the squeeze, hold, charge the weapon, slow release cycle at least five times, preferably 10. The hammer should never fall during the slow release. If it does fall during the slow release, contact Giessele immediately about what needs to be done to remedy the situation. They have a stellar reputation and should be able to help you quickly.

I did the function test you outlined above. I did not have any malfunctions. I also pulled the charging handle about 20 times and let it go and the hammer never came forward.

I think you hit the nail on the head with the safety switch. The bolt moving forward and locking is just so jarring that the whole gun moves forward in your hands. Its almost like recoil, but going forward instead of back. If the safety was on, it may not have happened. I think the bolt slamming forward is rattling the hammer off the sear. This would explain some of the double fires that I thought were bump fires. It may not happen when its cold and I'm performing dry tests, but the heat from live fire may be causing something to swell out of spec.

The next time I go to the range, I am really going to focus on the trigger discipline and ensure that I am following through on the trigger pull and retaining the trigger in the full rear position every shot. I am hoping it was just a fluke and will never happen again, but if there is a problem, I'm sure Giessele will make every effort to help troubleshoot and repair the issue.

[grumpyMSG]

If that rifle went off when you manually charged it or it went off when you hit the bolt release, you need to contact Giessele immediately for their advice/ assistance.

Next time you head to the range, start by turning the gas system back on. A zero with it turned off will result in a different impact point than when it is turned on. It will be slightly different because the muzzle velocity will be slightly higher, I would speculate just a few feet per second, but more importantly the gas system will begin to take the gas and start to cycle the rifle as the bullet is still leaving the muzzle. Believe it or not, gas on or gas off, your shoulder will be receiving the same amount of recoil energy. The same charge is going off as the same bullet weight goes down range. The difference would in the feeling. With a manually cycled rifle it would be more of a jolt, with an AR some of the energy will be stored up in the buffer spring as the rifle cycles, there will be less of a jolt when the buffer moves all the way to the rear. The rest of the energy that was stored in the buffer spring will then be transferred to your shoulder as the spring pushes the bolt carrier back forward. Any autoloader basically functions in a similar manner except some don't have a buffer and you have either a completely collapsed spring or metal on metal bump at the fully rearward position. The best analogy I can give you is it is like a punch versus shove. with the same amount of energy.

Soldiers and Marines have followed the same basic safety procedures on the zero range for years. When the rifle is not in your hands, the safety is on, there is no magazine in the rifle and bolt is locked to the rear. If you are working on the sights or scope it is in the same condition. If you are down range checking the target it is the same way. Both Soldiers and Marines have no problem dropping a magazine, inserting a new one and releasing the bolt, and return to engaging targets. It quickly becomes second nature, but that is the last thing you need to worry about on the zero range. When you fire your rifle, squeeze and hold the trigger, let it cycle and then release it once the bolt is fully forward again.

The whole bump fire thing and Slidefire stocks may be fun to play with, but the have little practical purpose other than to expend ammunition. I can't touch what Larry Vickers can do with skills or the ability to get the equipment, so you can learn a little from a master:
http://www.youtube.com/watch?v=cosc-RO_oMg

[0ne5hot]

Pro Tip: Don't leave your laptop unattended without locking it...even at home.
My brother just started a prank war. This is not the only forum he posted on.

[MarcSpaz]

I love when people leave their workstations unlocked at work. Not long after, emails go out about them buying lunch for everyone or they publicly profess their love for a manager. Ahhh... Good times.

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