Trigger Problems

[Leathermarshmallow]

I took my new rifle to the range today. It functioned flawlessly for about 300 rounds. Then it suddenly started malfunctioning. It would extract and load every time, but the trigger would not reset and it would not fire. If I ran the charging handle and expel the shell that was in it, it would reset the trigger and it would fire the newly fed shell. Sometimes if I pulled the trigger repeatedly, it would fire. Then I tried three different magazines, same problem. Then it began working fine again for about 1 magazine and then started the same thing. I am wondering if it is fouled up somehow. My son has one like it and he has literally thousands of rounds through it without a single hickup other than the occasional dud round.

I hope someone can tell me a solution. I dread trying to send it in for repairs.

 

[Rustpot]

It sounds like a disconnect or hammer follow issue.

Remove the upper receiver and set it aside. Hold the lower normally, set the gun to fire, and hold the thumb of your other hand just above the hammer. Pull and hold the trigger, and catch the hammer with your thumb. Press the hammer back down. Release the trigger. Does the hammer pop back up a fraction of an inch, or does it stay where you pressed it, or does it move as soon as your thumb moves off of it?

The 15-22 uses cheap AR trigger components, and there are bound to be out of spec units in producing parts for price instead of quality.

Edit:
Found a video that should help. The 15-22 trigger components are the same.
http://www.youtube.com/watch?v=TwcoKtWNtxM&feature=player_detailpage#t=97s

 

[Dragon88]

Yes, you need to do a functions check of the trigger group. Here's a video that shows what is described in the post above mine. Skip to 10:46:

DIY AR-15 Build - Trigger Group Installation - YouTube

This guy doesn't have his safety installed, but of course place your safety in the Fire position to do this. To functions check the safety: cock the hammer, flip it to Safe, and you should not be able to pull the trigger. Never try to force the safety to Safe with the hammer forward.

 

[Leathermarshmallow]

Thanks for the info. I will try it out and report back.

 

[Leathermarshmallow]

Well, I tried the trigger check as you all indicated. It appears to be working as it should. I hope that since it was not a constant thing, that maybe it just got too dirty. I will clean, oil and take it back to the range to determine if that was it.

Thanks for your help!

 

[Jammer]

If, as you say, the trigger group is working okay, then another suggestion is to pay particular attention to how the mags are loaded. Make sure the bullets are staggered properly in the mags. This seems to resolve a lot of reported loading problems....hope this helps.

 

[ragingyeti]

What ammo are you using? It could be short stroking so that it moves far enough back to eject and strip the next round, but not far enough back to reset the hammer. Try different ammo and see what happens.

 

[Hobie1]

When you say new..

Greetings,

Is this a NIB purchased or lightly used new? Did you give it a complete cleaning/lubing before taking it to the range?

It's not a mag issue since the gun is ejecting and loading the next round consistently. As was mentioned, ammo could be suspect but then the following wouldn't happen if the gun is short stroking.

You said you repeatedly pulled the trigger and it fired. That means the hammer was back engaging the sear. Have you done any trigger mods.? If you have, undo them and try shooting it again. If not and a good cleaning/lube doesn't cure the problem, stop and send it to S&W.

Hope you get it sorted out soon.

Hobie

 

[chuck s]

This stoppage is always a mystery to those used to the M16/AR15 system! The M&P15-22 fire control system was lifted completely from the standard AR15 and consequently has the same bolt carrier travel requirement to cock the hammer.

In the M16/AR15 system with a comparatively very long recoil stroke the hammer is cocked before the last fired case has been completely extracted from the chamber so if you get extraction and ejection you should get cocking (barring other problems). Cocking happens long before the bolt is far enough back to feed the next cartridge so an extremely rare short stoke can produce a click but not a dead trigger.

The M&P15 needs this same bolt travel to cock. The case is extracted and ejected before cocking occurs. In fact, cocking occurs only after the bolt has traveled past the point the next cartridge in the magazine will feed. If the M&P bolt "short strokes" the rifle can extract, eject, feed, and never cock the rifle.

Put an empty .22LR case in the magazine. With the magazine OUT of the rifle drop the bolt and dry fire. (The chamber should be empty, rifle uncocked, magazine with dummy round in the rifle.)

Ease the bolt back. Verrrrrrrrry slowly. Might take two hands to control it. Listen for the hammer reset click -- the trigger will jump forward -- and watch and listen for the click announcing the case in the magazine is ready to feed. The first click will be the cartridge popping up to the feed position -- before the rifle is cocked. If the bolt goes forward at this point the cartridge will feed, but the rifle ain't cocked. This can't happen with the M16 but can with the M&P15-22.

The ill-advised use of a needless rubber "buffer" in the bolt group will cause this as my testing confirmed. Binding bolt/rails, improper lubrication (never, ever use grease), and weak cartridges can all cause this. As can manufacturing defects if the rear block of the bolt carrier is too thick or not mounted properly.

I believe this is the second case of this in the past week.

-- Chuck

 

[Hobie1]

Interesting

Thanks Chuck! I, for one, just learned something.

How about the repeated pull of the trigger getting it to fire? That's the one thing was a bit confusing.

Hobie

 

[Leathermarshmallow]

Wow! You guys are awesome! I have learned alot. I am at work right now, so I can't go try it out. But yes, it was new in box and I have done no modifications to anything. My son has the same rifle (different color) and his has functioned flawlessly from round 1. I am hoping that all it needs is a good cleaning and lube job.

Thanks for all of your support!

 

[chuck s]

Suggestions for a "dead trigger."

1. Place the selector on SAFE. It can't go on SAFE unless the hammer is cocked. The trigger portion of the sear moving up and engaging the hammer drops the trigger tail far enough for the selector to block it. Do NOT force the plastic M&P15-22 selector or it'll be ruined and may not prevent accidental firing. If is goes on safe leave it there. Either way proceed to #2.

2. Maintaining the muzzle down range in a safe direction -- remember the chamber is loaded! -- push out the rear take down pin and open the receivers. Very easy to note if the hammer is cocked. Or if the trigger resets you'll hear a click.

3. Check is the disconnector. If the disconnector spring was inserted upside-down (the wide section goes in the trigger first) the disconnector will frequently fail to function. If the trigger is held back and released only after the bolt has returned to battery the hammer will ride the bolt back down as the sear never engaged. This can happen with the 5.56mm versions as well.

4. Reloaders of the 5.56mm versions of these rifles sometimes experience loose primers in this area which cause trigger problems but it takes an incredible amount of crud in the lower receiver to cause the same problems of a rogue primer.

-- Chuck