M&P 15-22 fires without touching trigger

Hi all,

Went to the range today to try out my new M&P 15-22. Purchased last weekend and haven't done anything to it other than wipe it down and add some lube to the bolt.

Using Federal Bulk, the one S&W magazine that came with the rifle. I ran through the first magazine myself without issue. Safety on, mag in, ping pong paddle to throw bolt forward, ready to fire, flipped to fire, pulled trigger till empty, back on safe, visually see bolt is locked back, magazine removed, put it back on the bench and then reloaded the magazine for my wife.

My wife get's it, repeats the same steps as above, only this time she get's a click and nothing, she waits, nothing. She puts the rifle on safe, pulls the charging handle back, only it wouldn't go back. She ejects the magazine and set's it down and looks back at me and asks for help. I pick the rifle up, try to rack the charging handle, nothing. Put the magazine back in, try to rack the charging handle, nothing. I flip the safety from safe to fire, and the rifle goes off without my finger touching the trigger. I put it back on safe, dumped the mag, locked the bolt back, checked for any other round in the chamber and set it down. I've never had a rifle do that before, ever. There's a first for anything I suppose.

What my wife and I are trying to figure out is why. She's immediately lost confidence in the rifle and went back to her 5.56 AR (S&W M&P 15 MOE) as the last .22lr I had (GSG 5-22) would jam on her every single time she touched it, giving her somewhat of a complex. Regardless, I'm concerned myself as I was unable to replicate it again, no matter what I did. Separated the lower from the upper, tried to put pressure on the hammer, anything to get the hammer to drop when flipping the safety switch and not touching the trigger.

Has anyone else experienced this type of malfunction? We thought it could have been a slow burn issue with the ammo but the sheer coincidence of my flipping the safety switch from safe to fire and the round touching off seemed too far out in left field.

I'd hate to have to send this brand new rifle back to Smith, I just picked it up, but if I have to then them's the breaks.

Not sure exactly what the problem is. The one issue I can see is with your wife placing the weapon on "Safe" after pulling the trigger. The gun is new to me as well but, the directions say to pull back on the charge handle first. The safety can only be engaged when the trigger is "hot". I would assume the first round was a dud, she should have ejected it then engaged the safety. Maybe something got jambed from forcing it into "safe" and then it released when you switched to "fire". I would assume that's the same reason you couldn't pull back on the charge handle (safety was engaged).

This is just my observation, like I said, I'm new to this gun as well. Hopefully someone with more knowledge will chime in with a more definitive answer.

First of all, glad to read no one was injured and good safety habits prevailed.

How long from the (presumed) firing pin strike and the round discharging? It sounds to me like a hang fire, which could take up to 30-60 seconds. In any event, a call to customer service tomorrow AM to discuss this seems in order.

It could have been a hang fire, but I think it may have been something else.

It should not go on safe after pulling the trigger, so that is concerning, either it was forced or something hung up and the hammer didn't strike the firing pin. When you switched it back to fire it released and fired (since the trigger was already pulled). This is probably why the charging handle was 'locked' too.

Have you inspected the BCG and FCG for anything wrong?

This could obviously be a dangerous issue, especially in the wrong hands, so proceed with caution and if in doubt send it back to S&W.

sounds like your wife did something out of sequence. Like others said, you can't put the safety on if the charging handle isn't cycled.. or the bullet didn't fire after pulling the trigger.. I'd inspect the FCG, check the safety for function, if it checks out, back to the range .. bottom line, if we are safety conscience, nothing bad can happen.

Sounds like something with the FCG. have you done a functions check?

It is hard to be sure since you are not able to replicate the problem. I have heard of something similar happening.

I remember reading that on someone's AR, when they changed out their pistol grip, the bolt was too long and was interfering with the safety selector switch causing a similar problem. I don't have access to my 15-22 right now, so I don't know if that is even possible on these guns.... Just what I read.

I will see if I can find some other info.


edit: a quick google check. I came across this post. http://forum.pafoa.org/general-2/22588-m16-issue-weapon-fires-when-safety-selector-switched.html

I thought it could be a hang fire, first one I ever experienced in my life ever if it really was the case.

I did not see anything wrong with her operation, she's very familiar with her regular AR.

What she did with the bolt back and locked, trigger on safe, inserted a mag, pushed pingpong to throw bolt forward, chambered a round, flipped trigger to fire, pulled trigger, nothing happened, flipped to safe, she tried to rack the round out with the charging handle, the handle would not budge. Dumped the mag, tried to rack again, nope. That's when she set it down and looked at me. I tried to rack a new round with the charging handle and it wouldn't budge. I had then inserted the same mag, tried to rack, nothing, then I flipped it to fire and the gun went bang.

In any case either it was sheer coincidence or there is some sort of problem with the safety/trigger, or I should go buy a lottery ticket, I'll give S&W a call tomorrow and see if they can shed any further light on it. There's not a whole heck of alot of moving parts there where it could get complicated but then again stranger things have happened.

I did a function check on it before I brought it to the range and everything checked out fine. Brought it home and again, function checked it and everything worked fine. One of those things I can't seem to let go of today even though the mrs is telling me to let it go till tomorrow

Wonder if the Safety wasn't fully off n the trigger pulled then put back to safety. Reading the manual on proper usage of things is mostly an important thing to do. Check to see if the trigger and safety work properly a 100 times in this scenario before sending it to S&W.
It is easy for the finger to pull the trigger when meaning to eject the magazine. Keeping the finger above the trigger comes with practice.
Most obvious was the action was fouled by a shell casing loaded or not.
Most obvious is the round was in the chamber and it should not have been there. Right ?

Maybe the weapon was out of battery, but you would never be able to put it into safe mode once the trigger is pulled without the gun going through a full cycle. If you had a hang fire it will go off at a later time, but you two handled the rifle together and that would take more than a few seconds to do so per your statement. Sounds more like a user malfunction than the rifle doing something wrong. I would keep shooting it, but not passing it between users until you are sure it is not a mechanical failure. Being able to put it into safe is a huge clue to what is going on with your weapon.

I have had allot of experience with the stock AR trigger. I can tell you that the location of the trigger and hammer are very critical and if either is out by .01" the gun will not function properly.
What I think happened is something I have seen before. When the trigger was pulled the disconnector was caught on the hammer. Normally they just miss but it is possible to get caught. When you put the gun on safe you actually reset the trigger because the safety pushes the trigger forward. The bold will not go back because the hammer is not fully cocked and is blocking the bolt. When you took the safety off the trigger moved back just enough to release the hammer and bang.
Take the upper off and just grip the lower. Take the safety off and pull the trigger while holding the hammer so it doesn't slam forward. Keep the trigger pulled while re-setting the hammer and watch how the disconnector works. Now release the trigger and watch the hammer get caught by the disconnector and pull the trigger again while carefully holding the hammer so it doesn't slam forward. Repeat, repeat, repeat, keep doing this as fast as you can without looking and eventually you will get it out of sequence and the hammer will get caught if there is a problem.
Of course if it never gets caught the gun is good and disregard everything I said.

Check your hammer and trigger pins. these have been known to walk to the left or right. Make sure they are centered within the receiver. There is a small wire (J spring) in the hammer that keeps the hammer pin captured and centered, but sometimes it fails causing the hammer pin to wander. This might cause problems with the hammer, sear, disconnect alignment.

Thanks Rundover!

Mine is still misfiring after just coming back from S&W.

It also has a lot of light strikes now that they replaced the bolt.

Maybe this time they will look a bit closer for the problem.

.

Lost Lake, guns are mechanical and as such you have parts rubbing against other parts. Anything that moves against another part must be as friction free as possible and the more the better. As you inspect your weapon look and feel the moving parts to be sure they are smooth and not gritty feeling. Light strikes can be caused by a number of things. You should systematically look at all the parts that are associated with this.
Firing pin - Pull the pin and inspect the pin and the channel. Everything should be clean and smooth and oil free. Dirt or oil in the firing pin channel will slow the movement of the firing pin causing light strikes, which sounds like your problem.
The hammer spring - Allot of people swap out the the hammer spring for a lighter spring. I don't understand this because a lighter spring will give you lighter strikes and be less reliable. I think this mod is done to lighten the trigger but a trigger that is set up correctly will not make a difference how strong the hammer spring is. Also make sure the spring is installed correctly.

Pin's haven't walked. I just bought the rifle a week ago and had not fired it till this past weekend. It was purchased brand new from a dealer.

Finger was not on the trigger, was nowhere near the trigger, or in the vicinity of the trigger guard.

In fact I asked the range we went to for footage of our session and we could visually see that my finger was not in/on/around the trigger when the switch was flipped.

It was not OOB either but was very strange that the charging handle could not be pulled back with a round chambered.

I'm going to take it to the range myself again and dump a few more hundred down range with it and see if it doesn't give issue.

I did do the trigger test 100 times and nothing managed to hang up or act weird either. It's just that not knowing feeling that I can't shake.

Pull your lower and see if the hammer has any type of hangups, It is a little hard to perceive that it could be put in safe mode after a trigger pull and the bolt not cycling. Just not physically possible.

U may have foreign material or damage to the lower unit. Look it over closely, if UR handy take it apart and inspect all parts for something unusual. I just saw an XDs with a broken striker guide so anything is possible.

been thinking about this. the safety will go into fire w/o the hammer being cocked if the spring and detent pin are not installed or installed correctly in the pistol grip. i had forgotten to install that part once and it will go from safe to fire with very light pressure since it is basically being held in place by friction.
you could check your spring and pin just to check.

that's all i got on this one.