Failure to feed problem

[jayferguson]

fixed!

ok... I tried different combination of buffers, spacers and buffer springs... and on the 3 try... voila! the beast now works perfectly with my reloads and factory ammo!!! I used a heavy buffer spring with the original s&w buffer...

jay

 

[rojodiablo]

Interesting Bassaro!
I will have to look into that if mine keeps having issues. One would think that S&W thought that through?

It really depends on who was making those barrels for them.

There has been a few things you would have thought they could have paid more attention to with this particular issue.

Bassaro's fix is one of the possible fixes. If you had no issues with the mags in the beginning, then its' hard to discount them after only a couple of loading cycles. As to ammo, a couple possible issues have been bantied about: The easy one, is the ammo underpowered. If the rifle is functioning correctly, that should not be an issue, with almost any commercial ammo you put thru it.
I am more thinking along the lines of the feed ramps and the overall length of some ammo might be just a bot too long. I would agree to try a Pmag and see how it stacks up with the ammo and how they feed.

Since the rifle already has some changes made to it, I am not sure what the primary starting point is for a fix until a few more questions are answered. How far does the rifle kick the brass out? At what position; as imagine looking down on you and the rifle, the barrel points toward 12 o'clock. 3 o'clock would be directly to the right. 5 o'clock would be over your right shoulder. This will help a bit.
Any scarring on the brass? Is it repeatable, and can you find where the scrapes are being made; this tells which part of function is causing an issue.

 

[fstkmaro]

I also have a feed problem!

I have had a severe failure to feed problem with my new M&P 10. The only mods to mine is the addition of a scope. In looking at the rounds that fail to feed, I see that they are bent at the joint of the casing neck and the bullet. This leads me to believe that the tip of the bullet is getting stuck somewhere when the bolt tries to load it. Upon further inspection, I looked at the chamber and I see that the barrel insert into the upper appears to be a bit too far in. This creates a ridge that is more noticeable on this gun than on any of my other ARs. The picture below illustrates what I mean. I will go to the range again today to try some winchester gray box rounds to see if that improves a bit but judging by the way that the un-fed rounds look after getting stuck, I am afraid I may have to give S&W a call to try to figure it out. To the OP, I am also in MA, not sure how far from me but I would like to get some insight from your experience. Also, if someone else can look at their M&P10 and can tell me if theirs look similar, that will help.
The same ammo on my M1 has no issue whatsoever
Thanks in advance

Jim

 

[rojodiablo]

I have had a severe failure to feed problem with my new M&P 10. The only mods to mine is the addition of a scope. In looking at the rounds that fail to feed, I see that they are bent at the joint of the casing neck and the bullet. This leads me to believe that the tip of the bullet is getting stuck somewhere when the bolt tries to load it. Upon further inspection, I looked at the chamber and I see that the barrel insert into the upper appears to be a bit too far in. This creates a ridge that is more noticeable on this gun than on any of my other ARs. The picture below illustrates what I mean. I will go to the range again today to try some winchester gray box rounds to see if that improves a bit but judging by the way that the un-fed rounds look after getting stuck, I am afraid I may have to give S&W a call to try to figure it out. To the OP, I am also in MA, not sure how far from me but I would like to get some insight from your experience. Also, if someone else can look at their M&P10 and can tell me if theirs look similar, that will help.
The same ammo on my M1 has no issue whatsoever
Thanks in advance

Jim

HOLY COW!!! What an EXCELLENT set of pictures!!
This is a relatively simple polish job. Take a dremel tool with a small round polishing stone, and carefully massage all that. True up the edges of the barrel to the upper, and then afterwards, use a polishing wheel with some automotive rubbing compound (Rough compound) you will leave that junction slick and this is a problem which can be fixed in about 10 minutes total time. Be patient, and do not push too hard.

 

[fstkmaro]

Thank you rojo diablo. I figured it could be simple, there's however that feeling about a brand new not necessarily cheap gun needing such work. I would not mind it much had it been a hi-point gun but a S&W? Anyways, I may end up following your advice. Living in the people's republic of MA, I don't want to take the chance of anything going wrong with the shipment or return.
I will later post a pic of a damaged round.

Sent from my SM-P600 using Tapatalk

 

[fstkmaro]

just to add some detail, here is a pic of a jammed round going in and the resulting damage to the round.

 

[copemech]

just to add some detail, here is a pic of a jammed round going in and the resulting damage to the round.

That looks much more like my bolt override condition. It never picked up the new round, just drug it in.

If action is running too fast or too slow, seems they will do this. How far and what position is it ejecting first round?

 

[fstkmaro]

The rifle ejects fine for the most part with cases lying about 10ft away from me. These pics were taken yesterday. I noticed that my FTF happened only with Winchester white box 7.62x51. I tried, PPU and Aguila besides the winchester. In my case, it appears that the bolt just starts to push the cartridge and looses grip. Possibly because the round is stuck on the ridge I showed earlier or maybe because the area of grip between the bolt and the round is too small. This latter one may indicate a problem with the magazine. The factory mag is a PITA, I have the habit of butting it against the bench a couple of times after loading it so that the rounds seat properly and has worked better since I started doing that.
Anyways, the damage to the round is clear on a relatively new gun.

 

[MistWolf]

just to add some detail, here is a pic of a jammed round going in and the resulting damage to the round.

This is is a bolt over, resulting from short stroking. Winchester White Box is loaded to 7.62 NATO specs which makes less pressure than commercial 308 ammo. If your rifle is running fine on commercial ammo, it's clear that your problem is NOT the feed ramps and the photos show that your ramps are ok.

S&W tuned the M&P-10 to run on commercial ammo because that's the spec hunting ammo is loaded to. If it were tuned to be used with 7.62 NATO ammo, it's possible it'd be over gassed for hunting ammo with sharper recoil than necessary. You can tune your M&P-10 to run on lower pressure ammo, but the result will be the same as tuning a 5.56/223 caliber AR to run reliably on low pressure ammo- when using full pressure ammo, recoil will be sharper and the reciprocating mass will bottom out harder

 

[apiccola]

Not sure if it means anything, but my old DPMS LR308 that shot everything without any need for mods had a barrel stamped 7.62 with a larger gas port. The M&P 10 barrel is stamped .308. Is there a relationship between the .308 designation and the smaller gas port?

 

[sgtsandman]

The .308 is the hotter round of the two, so my guess is that less gas is needed to cycle the BCG.

 

[apiccola]

Looking at Armalite and DPMS, their AR "308" model ads specifically address 7.62 NATO and .308, but the Smith & Wesson ads do not mention 7.62 NATO at all for some reason.

 

[fstkmaro]

This is is a bolt over, resulting from short stroking. Winchester White Box is loaded to 7.62 NATO specs which makes less pressure than commercial 308 ammo. If your rifle is running fine on commercial ammo, it's clear that your problem is NOT the feed ramps and the photos show that your ramps are ok.

S&W tuned the M&P-10 to run on commercial ammo because that's the spec hunting ammo is loaded to. If it were tuned to be used with 7.62 NATO ammo, it's possible it'd be over gassed for hunting ammo with sharper recoil than necessary. You can tune your M&P-10 to run on lower pressure ammo, but the result will be the same as tuning a 5.56/223 caliber AR to run reliably on low pressure ammo- when using full pressure ammo, recoil will be sharper and the reciprocating mass will bottom out harder

What's the difference between win white box and the commercial ammo you speak of? I mean besides the .308 and 7.62 issue? I don't shoot reloads unless white box is a reload
Also, I think the manual states that both types can be shot.
Thanks for the comments.

 

[sgtsandman]

White box tend to be military/government ammunition.

I've shot white box and been fine. Apparently, not everyone is so lucky. Just like any other firearm though, it seems each individual M&P10 likes some ammo better than others and hates others.

As an example, my Catamount Fury won't cycle with low brass and some low recoil high brass no matter how I adjust the gas block even though Century Arms and the Owner's Manual says I should be able to.

 

[MistWolf]

What ammo the manual says the rifle will shoot & function with and what the rifle actually shoots & functions with, are sometimes different things

 

[Mealman]

M&P 10 failure to feed

I'm new here but have used info so much I decided to join. I have a Smith M&P 10 also with many of the same problems listed here in this thread. I've added one Tubb's Precision AR-10 CS Buffer spring, a CMC 3.5 pound trigger group, and a 3-12 UTG scope. The trigger is very nice but I won't go into the install since that's covered here in another thread. When I use any .308 round I have zero issues and fairly good accuracy at 100 yards. That's any .308 I've used from Federal to PMC and a few in between. I've never had good luck with any 7.62x51 ammo. Failure to feed and failure to lock back after last shot. The only change to the system to affect it is the spring which made it operate smoother. This gun is for .308 and if you find it, hotter 7.62 rounds. I like the gun. I like to run .308 and now I'm looking at the right weight .308. From the threads here it looks like it's closer to 168grains then to 150. Please, since I'm new, let me know if I've missed anyone having problems with the .308 round not cycling the rifle correctly.

 

[MistWolf]

Actually, commercial 308 ammo is loaded to higher pressure than 7.62x51 ammo

 

[Mealman]

.308 pressure

Mistwolf. I guess I made an assumption that everyone here would know that .308 is a higher pressure,thus, it would cycle the bolt better with less fail to feed due to short stroking problems. At least that is my experience with my M&P 10 and seems to be a common problem. I'm thinking an adjustable gas valve would be the ticket like on the Ruger 762 and a few more. The gas port would be another place to look but I like to start with less drilling at the beginning of troubleshooting.
Thanks by the way. My shooting partner that has years of experience over me didn't know .308 has higher pressures.

 

[copemech]

Mistwolf. I guess I made an assumption that everyone here would know that .308 is a higher pressure,thus, it would cycle the bolt better with less fail to feed due to short stroking problems. At least that is my experience with my M&P 10 and seems to be a common problem. I'm thinking an adjustable gas valve would be the ticket like on the Ruger 762 and a few more. The gas port would be another place to look but I like to start with less drilling at the beginning of troubleshooting.
Thanks by the way. My shooting partner that has years of experience over me didn't know .308 has higher pressures.

An adjustable gas block will not help an undergassed gun. The issue is the gas port size.

You can allways gas down with an adjustable block, but you cannot gas UP, because it is running wide open now! It only receives what comes out of the port!

Please read my comments in the other related thread just below this one.

In the case of S&W 10, COMMERCIAL means US made hunting ammo and match ammo by US makers.

 

[Mealman]

An adjustable gas block will not help an undergassed gun. The issue is the gas port size.
I suspected gas port size but wanted to make it work without drilling. It sounds very good to have someone that has done it and had good results. When hell breaks loose it would be nice to know I can use 7.62 if I find it.

You can allways gas down with an adjustable block, but you cannot gas UP, because it is running wide open now! It only receives what comes out of the port!

Please read my comments in the other related thread just below this one.

Read them and now have a firm direction for this rifle. I'm sure there are others but when I do use match grade Federal I sure like the results. I was also looking at 168 to start and move up or down to get the results I need. I can load it myself after I get the mix I need.

In the case of S&W 10, COMMERCIAL means US made hunting ammo and match ammo by US makers.

Also thanks for the link to your thread. It helped a bunch!