S&W M&P 15 Firing Issue

[Mule0325]

Looking for help,

I have a S&W M&P 15 optics ready .223/5.56. My issue is; the first round will fire and chamber the next round but it will not fire the second. The primer of the second round is getting hit by the firing pin but only slightly "small strike mark". I have tried several different types of ammo and cleaned/looked at all parts. Any ideas out there of to what might be my problem? Thank you

 

[G.barnes]

Does the hammer drop when you pull the trigger on the second round. It might not be going fully into battery. The primer strike could just be from the floating firing pin. If you load one round at a time will it fire every time. If not might be a weak hammer spring.

 

[Mule0325]

No the hammer does not drop. It does not fully reset "spongy trigger". I've checked all springs all are good. Also note it is a new gun, less than 200 rounds fired. Yes it will fire if I load 1 round at a time.

 

[rbernie]

The free floating firing pin is making the primer dimple when the gun runs the bolt into battery.. The hammer is likely not resetting, meaning that the ammo is not cycling the action completely.

That could be the ammo, lack of lube, or a gas system problem. I'd try other ammo first.

 

[kwg020]

What's your ammo and did you look over the rifle and make sure EVERYTHING that needs lube got it. kwg

 

[Mule0325]

I have used the American Eagle, PMC XTAC and Remington ammo all with the same result. I have looked everything over, cleaned and re-lubed. I've checked the 3 washers on the pin housing and they are (gaps) properly spaced apart.

 

[G.barnes]

Before you start getting into messing with things call s&w they should take care of it.

 

[ApacheCoTodd]

The disconnector is not retaining the hammer during cycling.

Could be one or a combo:
Bad disconnector
Bad hammer
Incorrectly positioned firing group hole/holes

Picking up the next round tells us that the BCG is travelling far enough to "set" the hammer.

The hammer not dropping on the pull of the trigger tells us that the hammer is following the BCG forward.

 

[Blade First]

Have you conducted the standard function/safety check?

 

[CornCod]

Oh, and try a different magazine too.

 

[Ditch-Tiger]

Weak ammo or its not getting the correct amount of gas.
Not normal but, is it a brand new gun? How many rounds have you fired?
If its only a few I would suggest running some more. Your gas block might not have a perfect seal and is bleeding off. It may require a few more rounds to seal it.
Either way, Smith will fix it.
Sorry about your bum luck.

 

[red rick]

My brother and me bought new M&P MOE 15's in Feb. ( from different dealers @ a gun show ) .

His son took it out a couple weeks ago and he said he had a lot of misfires on each magazine ( 55gr. PMC Xtac fmj ) .

Shame on me , I have not tried mine out yet .

 

[goon]

Try the function check.

Make sure the rifle is empty, cycle the action, pull the trigger and hold it to the rear. It should "fire" (click). While still holding the trigger to the rear, cycle the action again, then let go of the trigger. You should feel the hammer shift from the disconnector to its proper position of being held ready to fire by the sear (trigger). Pull the trigger again and it should "fire."

If it won't do that, then it isn't functioning correctly. Try that and if it passes, we'll talk about other possible causes.

Easiest case though is to call S&W. They'll probably issue a repair tag and a shipping label - that's what they did last time I had to use their customer service. They did resolve the problem, so I've got no qualms about buying another S&W.

 

[Mule0325]

Goon,

The function check does not pass. After the second cycle of the action while holding the trigger, after releasing the trigger the hammer did not shift from the disconnector to its proper position, I had to tap on the back side of the trigger for it to go forward and then it fires. Thank you for your assistance, what would I have to do to correct this issue or would it be best to send back to S&W.

Again, thank you,
Mike

 

[goon]

For whatever reason, it sounds like your disconnector isn't releasing the hammer like it should. That's good news because we're getting to the problem and now we know it's not something wrong with the upper. If you pull the upper off and take a look down inside the lower, especially if you can post a pic of what you see, we might be able to help you diagnose the problem.

Since it's under warranty from S&W, it also might be a good idea to just let them handle it. I've found S&W to be pretty prompt about getting things fixed - about two week turnaround - and swapping an AR hammer/trigger/disconnector is literally about a five minute job.

 

[Mule0325]

Goon,

Pictures attached.

 

[Mule0325]

Thank you Goon issue fixed

Goon,
Tthank you for leading me to the problem! While taking the pictures I noticed the pinched spring on the left side of picture #2. I re-adjusted the spring to look like the other side and the problem is solved! Thank you for the help.

Mike

 

[goon]

I'll be damned!

I couldn't see anything that looked obviously wrong in your pics, not even comparing it to a half-assembled stripped lower that I dug out and have on the desk in front of me right now for comparison.

But I'm glad our discussion helped you find the problem. I bet you'll enjoy your AR a lot more now!

 

[Mule0325]

Goon,

if you look at the second picture, the top of the picture where the where the long end of the one spring is pinching in between the two loops in the spring that wrap around the pivot point of the hammer. That was causing the hammer pivot point to bind against the body of the lower. I lifted up the long spring end and slid the double wrapped spring over towards the hammer so it looked like the bottom view on the other side of the hammer. The function check passed after that and she fired like a champ again.

 

[sugerwater]

Did the rifle come from the factory like that?

 

[Mule0325]

no it did not come from the factory like this. This issue started the second time I took it out to shoot it, the problem occurred after the 17th shot during the 2nd outing.

 

[MachIVshooter]

no it did not come from the factory like this. This issue started the second time I took it out to shoot it, the problem occurred after the 17th shot during the 2nd outing.

Hmmmm. You certain about that? There's really no way the springs could end up like that on their own if everything is in spec.

Perhaps it just took awhile for it to cause a problem, but I'll say with 99.99999% certainty that it was improperly installed to begin with.

 

[goon]

Yep, it's pretty unlikely that a spring in an AR fire control group could jump to that position on its own. Probably just a little out of whack when it went in.

But I'm glad Mule0325 got it figured out.