Unintended discharge from AR15
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Hair Trigger
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Probably wasn't a slamfire from OP's description of the event. There was a passage of time from the round chambering to the discharge, only after he had aimed downrange and flipped the safety off. A slamfire would have been instantaneous when the bolt closed into battery. He didn't mention loading from a magazine, but single loading an AR is not really easy; if all you want is a single shot, it's much easier to load one round into a magazine and load the gun from there.
I shoot a M1A quite a bit, and they have somewhat of a reputation for being slamfire prone if single loaded, or if primers aren't fully seated in the case. Although I've heard tales from some shooters, I've never experienced one myself, even though I have single loaded many times. I just never drop the bolt from the locked open position.
Oldsalt66
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I’ve been shooting ARs for quite a few decades and I’ve never encountered an occurrence like that.
Smith&Wesson has a “lifetime service policy”, and I urge you to contact the company.
Kudos for keeping the muzzle in the right direction.
Smith&Wesson has a “lifetime service policy”, and I urge you to contact the company.
Kudos for keeping the muzzle in the right direction.
minconrevo
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AR 15 Action Group Finicky to Modifications
Many perfectly safe AR 15's have been "improved" by owners to become unsafe. A new standard weight trigger spring might fix it. A little too much stone work on the sear begets occasional doubles. One fix mentioned is to contact S&W and mention "safety problem". Another fix is simply to replace the fire control group with one of the drop in cartridge style units. You won't be without your banger that way.
Many perfectly safe AR 15's have been "improved" by owners to become unsafe. A new standard weight trigger spring might fix it. A little too much stone work on the sear begets occasional doubles. One fix mentioned is to contact S&W and mention "safety problem". Another fix is simply to replace the fire control group with one of the drop in cartridge style units. You won't be without your banger that way.
Maybe nobody else has heard of, or, see of that happening before, but I have....on a couple of occasions. And, each time it has been from someone messing with the stock FCG. Both times it was caused from stoning/'polishing' the angle on the trigger bar where is contacts the 'notch' on the hammer. Other 'issues' I've seen were from stoning/'polishing' the rear lug on the hammer where it contacts the disconnector. You mess with that angle on a MilSpec trigger and/or mess with the hammer, you're just asking for problems. From multiple unintended shots, to the hammer dropping when the selector switch is moved from 'Safe' to 'Fire", to full 'run-away' until the mag empties. I suppose that it is possible that it could happen with a factory, unmodified, MilSpec FCG, but, not very likely, or very often. Unless you know what you're doing, don't mess with FCG's on any firearm.
You can just replace the parts on yours, hammer spring, disconnector spring, trigger spring, disconnector, hammer, trigger, selector switch, and so on, and your problem will probably be solved. But, if it were me, for piece of mind, I would replace the entire kit and kaboodle with a new MilSpec FCG, or, a new aftermarket FCG of your choosing.
Continue to keep that muzzle pointed in a safe direction, update when you get it squared away, and carry on.
You can just replace the parts on yours, hammer spring, disconnector spring, trigger spring, disconnector, hammer, trigger, selector switch, and so on, and your problem will probably be solved. But, if it were me, for piece of mind, I would replace the entire kit and kaboodle with a new MilSpec FCG, or, a new aftermarket FCG of your choosing.
Continue to keep that muzzle pointed in a safe direction, update when you get it squared away, and carry on.
I appreciate all your inputs, as I have remanded custody of said suspect firearm to a truly talented and accredited AR15 gunsmith for just a cursory FCG and whole unit inspection. I WILL say that after attempting to get this to occur WITHOUT a round in the chamber, I failed to get the hammer to fall. Seems to only do this when a round is chambered with the action locked open and after I chamber the round and select FIRE, does it occur. That being said, I am worried about the ability to move the selector to "safe" prior to even setting the action back. So... my gunsmith will approach this from two ways: Either contact Smith or just repair whatever is goofed up. I appreciate all the input here. There is a great, vast ocean of experience in this location. Thank you all.
cmj8591
Member
Your friend should have kept the gun and got rid of the woman.
^^^ A common, and tragic mistake. 
Zman10915 said:
You didn't mention that initially. If "setting the action back" means cocking the hammer/racking the bolt, that suggests something seriously out of spec in the trigger group/safety. An in spec trigger group [in an in spec receiver] will NOT allow the safety to be "on" with the hammer down. Perhaps some misguided individual "fixed" the perceived problem? Alternatively, some massively bad parts were installed at the factory and someone botched the function check. Or, the receiver is out of spec.
Just for the record, after cleaning, the proper function check for the AR pattern is: hold the trigger back and rack the bolt, allow the trigger to reset and be aware of the force needed to dry fire. Next, rack the bolt, apply the safety, attempt to dry fire; then, move the safety to "off" and dry fire. There shouldn't be a noticeable difference in the force needed to dry fire. If there is, the trigger group needs parts replacement. And: the safety should not be able to be placed "on" with the hammer down/in fired position. You can make that check after the first dry fire.
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I have had possession of a relatively new (I'm 2nd owner) AR15 S&W and just had something occur the other day that is really rather disconcerting. After chambering a round (55 grain SP) I aimed the weapon downrange, and when nearly ready to fire, placed the safety from off, to 'fire." Without getting NEAR the trigger, the weapon discharged the round I had just chambered.
*** , eh? What causes this and how might I best fix THIS little problem that has caused me to shelf the darned thing until fixed...
Whatever you spend to remediate this is well beyond well worth it! You can't sell it like that in good conscience and you can't really use it safely. Spend the money, whatever that is and make it right. The alternative is perhaps a life!
Thank you mod34. THat'S why the firearm is in the hands of respected gunsmith here, in these parts to find out what I might do to rectify this situation.
Yes.... I volunteered to let the original owner have it back if he dumped the reason why he got rid of it in the first place. NOT a good trade, having seen the reason in first hand. NOT a good reason at all, actually, I will see this through and keep it. I love the firearm and will spend what it takes to make it safe.
Thanks to all!!
Dave
Yes.... I volunteered to let the original owner have it back if he dumped the reason why he got rid of it in the first place. NOT a good trade, having seen the reason in first hand. NOT a good reason at all, actually, I will see this through and keep it. I love the firearm and will spend what it takes to make it safe.
Thanks to all!!
Dave
M&P 15 forum-ers,
Is it possible that the previous owner moved (forced, actually) the safety from fire to safe when it was not supposed to me moved? Might be enough to let the sear slip when it is not supposed to.
Zmam10915, congrats on the new-to-you M&P and I'm sorry to hear about the unpleasant surprise at the range. Please post an update once your smith has put things right.
Chris
Is it possible that the previous owner moved (forced, actually) the safety from fire to safe when it was not supposed to me moved? Might be enough to let the sear slip when it is not supposed to.
Zmam10915, congrats on the new-to-you M&P and I'm sorry to hear about the unpleasant surprise at the range. Please post an update once your smith has put things right.
Chris
Short answer: NO! Should not be possible, unless there are some seriously out of spec parts in the trigger group. Or possibly an out of spec lower receiver.
The sear on the AR design semi auto trigger group is on the front end of the T shaped trigger. When the hammer is forward, the design of the hammer blocks the front end of the trigger from moving up. This causes an interference between the safety shaft and the rear of the trigger that keeps the safety from being put in the "on" position. There's a flat on the shaft that allow trigger movement when the safety is in the "off" position, but only with the hammer in the cocked position held by the sear.
I tried to do a diagram of the trigger layout but the cotton picking website won't move the diagram to the thread without distorting it.
The sear on the AR design semi auto trigger group is on the front end of the T shaped trigger. When the hammer is forward, the design of the hammer blocks the front end of the trigger from moving up. This causes an interference between the safety shaft and the rear of the trigger that keeps the safety from being put in the "on" position. There's a flat on the shaft that allow trigger movement when the safety is in the "off" position, but only with the hammer in the cocked position held by the sear.
I tried to do a diagram of the trigger layout but the cotton picking website won't move the diagram to the thread without distorting it.
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Rastoff
US Veteran
I didn't see this in the previous responses:
Did you call S&W? They will fix this for free.
Did you call S&W? They will fix this for free.
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Zman10915:
Dave, I hope you let us know how this all ends up. This has been a real interesting thread.
Dave, I hope you let us know how this all ends up. This has been a real interesting thread.
Dave,
I just saw this post today. I have heard of similar discharges over about 30 years of competition. It hasn't happened often, but once is two times too many. In the instances that I am aware of, it was a blown primer that got wedged in the FCG. Sometimes, the blown primer gets caught between the sear contact surfaces, and when the safety is disengaged, the hammer slips free.
I just saw this post today. I have heard of similar discharges over about 30 years of competition. It hasn't happened often, but once is two times too many. In the instances that I am aware of, it was a blown primer that got wedged in the FCG. Sometimes, the blown primer gets caught between the sear contact surfaces, and when the safety is disengaged, the hammer slips free.
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