ok this is the best way to describe my problem. A few months ago I bought an M&P15 sport. I then directly took it to the back of the store without cleaning it and put 60 rounds through it fine.

So I took it home, cleaned it pretty thoroughly, lubed it, and now it will chamber rounds, fire them, and then in the middle of a magazine every once and a while "click" and no boom. I have to rack the round out of the chamber and the crimping is loose on the rounds at the end of the casing. This was with both American Eagle 5.56 55gr rounds and Perfecta .223 55 gr.

This has happened on two different trips to the range. The first time I even had to take the upper/lower apart because a round got "stuck" in the chamber crooked. Today, I had a couple of misfires out of the first mag but then I ran 50 rounds out without any issues. I wish I would have brought more ammo out there because it wasn't malfunctioning for the last 50 but it still bothers me. And I don't blame the magazine because it happened with two different magazines the first trip and they are all brand new P-mags.

Could this be a "break-in" thing? I just find it odd that straight from the box I fired 60 out of it without any issue and now that I have it cleaned and lubed a lot better it is having issues. I know it is reassembled right and the gas ring notches aren't lined up either.

Should I send it in or give it more time?

It doesn't sound like a break in thing to me.

Have you field stripped the bolt carrier and cleaned it? Are there any obstructions that would prevent the firing pin from free floating in the BCG? Hinge open your upper and lower. Look for any odd witness marks on the lower, in the upper receiver, on the BCG. See if something is dragging.

That's about as far as I would take it, then I would call S&W CS.

__________________
-John

yes I've completely taken apart the BCG and cleaned it with solvent and oiled the hell out of it before both times it had malfunctions. There's no obstructions or anything I can find. Looks like an AR-15 should look inside. I've even cleaned the buffer tube. The only thing I haven't done is mess with the gas system but I don't think it is obstructed or it wouldn't run at all.

I'm a pistol person, kinda new to semi-auto rifles, so I'm not all that familiar with it (why I got a sport because I didn't want to spend a fortune on something that I was just getting into).

Sounds like you're using good firearms common sense in diagnosing your issue.

Call S&W. Better to be safe than sorry. I'd be wary of an out-of-battery primer ignition or any other problem.

__________________
-John

Yeah I figure I'll call them and send it in. From what I've been reading it could be that the chamber is not sized right to fit the round possibly?

I don't know but at almost 50cents a round to try to "break it in" it isn't a cheap diagnosis. I figure I'll let them figure it out on their dollar considering one of the biggest reason I like S&W is their good customer service.

Your Bolt Carrier should be BONE DRY except for the rails that locate it in the receiver. If you are lubing the Bolt inside the Bolt Carrier that is a PROBLEM. That lube will collect powder residue and create a Gum.

I would also suggest soaking the bolt for a while and using toothpick or similar items to totally clear the channel for the Firing Pin. Because if you've been lubing this area it's likely that it's become packed up with something that resembles Tar and gumming up the firing pin.

Tip, when assembled with the firing pin locked in place by the retaining pin you should be able to hear the firing pin rattle back and forth as you shake the Bolt Carrier group. If you can't hear that rattle, start over and get everything cleaned properly.

PS: they aren't cheap but a Nickel Boron plated Bolt Carrier can allow you to run your AR15 without ANY lube at all. This means us Belt and Suspender types can use a very light application of oil to the rails and not see any wear in the receiver.

My experience has been 180 degrees opposite scooters. I run my range guns wet. When I shot local marches competitively, I'd start the season with the bolt and carrier wet almost to the point of excess. After each match, I'd place a couple of drops of CLP in the vent holes of the bolt carrier. The gun wouldn't get cleaned until after the season, which could be as much as 600 rounds. Never had a misfire.

I don't believe in "break-in" periods. If a firearm is put together and designed with proper tolerances, it should run from the first shot. I do realize that occasional burrs from the manufacturing process may need to wear off, but more than a couple of hiccups when you first shoot it is unacceptable.

I'm with Michigan and run my ARs with the BCG wet. For what it's worth, the been-there-done-thats who are teaching today say the same thing when dealing with stock ARs/BCGs. I have no experience with the advances coatings, but I would suggest you get with S&W and the the gun running in stock form like it's supposed to before investing any more money.

If your AR has a 5.56 chamber, do your breakin with M193 ammo. It is full power and will run the rifle as designed.

Take your chamber brush and some Hoppes #9 and scrub the chamber, then dry with several dry parches.

And run the bolt carrier assembly dripping wet with CLP. A dry BCG, a new gun, and underpowered ammo will turn any AR into a jamm-o-matic.

The American Eagle 5.56 is m193. It is dripping wet in Hoppe's 9 lube. The bolt, the bolt carrier, and I even put a tad on the firing pin. Hoppe's 9 has worked for every other firearm I've ever had. Scooter's theory about having a dry bolt doesn't add up because this thing jammed up on the 3rd shot of m193. It was lubed but it was 100% clean. In fact it had problems when it was clean, but the last 50 rounds shot off without a hitch.

I'm calling S&W today and having them shoot it on their dime until they get it right. I didn't do anything wrong and it is all brass, decent ammo that should be going through.

I go with this. I have 3 Sports, one with about 4500 rounds thru it, the second with about 1500 rounds thru it, and the newest with 300-500 rounds thru it, and I run all three wet, Wet, WET, WET. All but dripping...

That's around 6000 rounds thru three guns and I've had one FTF...and that was the ammo, not the gun.

__________________
Bob | KM4DEO
Sport | Glock 22

Sounds like we need a lubrication update thread. FWIW, I've been running my Sport pretty wet, but now I'm going to try it drier with the BCG dry except for the rails to see how it runs.

__________________
Still carrying my S&W 642

I also use Hoppe's 9. It's good stuff. However, it is a solvent, not a lube.
I use it to clean and then lube with a product that is a lube.
I like CLP (just short of dripping) as it keeps the crud in
semi-suspension and makes it easier it clean at the end of the day.

__________________
CSM, U S Army(Ret) 1963-1990

Make certain it is re-assembled correctly...doesn't take much to get them not acting right.
Gary

In your initial post you said you shot it NIB without cleaning it. These guns have preservative in the barrels that must be removed before putting the gun in service. Once you fire it with this stuff in the chamber, you have semi solid coating that forms.

If the bolt does not seat all the way, it doesn't cam all the way into the lugs, and the carrier blocks the firing pin from being able to go full stroke and set off the primer. This is a safety feature of the design top prevent OOB or partial lockup firing.

It doesn't take much, a resized case on a reload (I know, you had new ammo) where the sizing die does not touch the shell holder will cause this many times, and you can not see the difference in a good round compared to a bad round. So just a little semi-solid crud in the chamber will do the same thing.

Without seeing the gun, this is most likely as the gun was shot with anticorrosion treatment in the bore.

That chamber brush does a good job, try it.

I know I sound like an idiot, but what chamber brush? I don't recall a brush being in the box.

While I don't agree with the notion that there aren't any stupid questions, your question isn't a stupid question. Until I owned my 15-Sport, I had no idea that an AR-15 chamber brush existed or what it looked like. S&W does not include any cleaning kit in the box.

This is an AR-15 chamber brush.



I affix it to a pistol cleaning rod. I either spray solvent into the chamber or moisten the brush with solvent, then brush away.

I wrote a post on all the AR-15 cleaning tools I own. It has a bunch of pictures and should be very helpful to you. If you have any questions, just ask.

New to AR's? Here are some tools I use to clean.

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-John

One suggestion about making sure the path of the firing pin isn't gummed up or blocked. I don't do it often, nor do I remember the last time I did this.

If the bolt is gummed up with old lube:

1. Remove the extractor. Remove the the rubber O-ring and spring. Set those aside. I don't want the rubber O-ring to get eaten up by step 4.
2. Use the pipe cleaner to clean out the firing pin channel in the bolt.
3. Use the CAT M4 to clean the bolt tail, firing pin.
4. I'll then hose the bolt off with non-chlorinated brake cleaner. I'll then insert the spray straw into the bolt tail and hose out the firing pin channel.

Use safety goggles. Hold the bolt away from you and angled so you don't get splash back. I keep my mouth closed and hold my breath. I do this outdoors.

I'll then use pipe cleaner to clean the firing pin path through the bolt. I'll use pipe cleaner to clean out the cam pin's firing pin hole. I'll use pipe cleaner to clean out the gas key.

Just in case, this is pipe cleaner.

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-John

Yes, the firing pin should move freely in the bolt. Gravity alone should be enough for it to move in or out.

When you do a tear down and inspect the bolt, check that the rings look good and not damaged.

Also, the "flick test" will tell you if your gas chamber is rough and needs breaking in. Basically, take the assembled bolt carrier group and push the bolt into the carrier as far as the cam pin will allow. Then "flick" the bolt like you would a gravity knife. The bolt should extend to the front as far as the cam pin will let it.

Some CLP on the rings and work the bolt in and out will alleviate a tight bolt/carrier fit.

Please explain the phrase "the crimp is loose at the end of the casing". Do you mean the bullet crimp or the primer crimp? If bullet, it hints at a feed failure of some type. This is generally a magazine issue. Note: AR magazines should be downloaded 2 rounds from full capacity for reliability reasons.

OK, I have to agree that taking a brand new firearm to the range without prior cleaning and lube is asking for problems. If you ran 60 rounds through it without issue, there's no issue with the chamber.

I've been using the AR system for ~40 years and I'm not a wet bolt type. I haven't worked in the sand box, but in all other environments, I've gotta go with a modified version of Scooters suggeston. The rails the carrier runs on should be lubed. The rest of the carrier body only needs enough lube to prevent rust. Note that I use the word "lube", not oil. I prefer a dry film lubricant so that the combustion gases don't turn it into carbon. However, others have been successful with other products. I do like to use moly grease (chassis lube) on the cam pin surfaces of the carrier-a little dab will do ya here.

The firing pin should run back and forth by it's own weight as someone else noted above. Do the bolt cleaning as JaPes suggests.

Since you noted you've "lubed the hell out of it", I suggest removing the buffer & spring and remove excess lube/oil/**** from the buffer tube/receiver extension. Look down in there and make sure nothing lurks in the tube to limit buffer travel.

IMO, the nylon chamber brushes outlast the bronze ones and are worth the slight extra cost. The "one product cleans, lubes and protects" stuff is beloved of those who manage supplies and/or carry all the stuff on their backs through the boonies. They're generally not as good as a product specifically designed for cleaning, or lubing or protecting.

Ok, I'm gonna get a chamber brush, clean the ever living **** out of the whole rifle with Birchwood Casey Gun Cleaner (solvent), then I'm gonna lube it up with Hoppe's 9 OIL (not the solvent) but not as much. It didn't need to be soaking wet out of the box to shoot 60 rounds, so I don't figure it needs to be soaking wet later. Also the last 50 rounds ran without any problems so I'm wondering if it didn't "shoot out" some of the excess oil? Other people are talking about running them soaking wet so I did so. After my next trip to the range after cleaning everything out as much as I can, I'm gonna call S&W and get them to look at it.

And the bullet crimping in the casing is the problem. The bullet will roll around in the casing, like it is loose. It does sound like a feeding problem but this happened with 2 different brand new P-mags.

I know it might not had been the best idea to shoot it out of the box, but I had done it so many times with guns that I thought I could clean out any of the packing ****. I inspected it before I shot it and it seemed bone dry.

Here. Follow this.


Substitute in your cleaner, lube, tools, etc.

__________________
-John

If it has started to run for you, then you might have achieved "break-in." Consider a synthetic lube such as Militec 1 or Slip 2000. Get a good AR cleaning kit that has all the required brushes as well as some pipe cleaners and a-tips. One of those bolt carbon scrapers would be something to consider cause it gets into places where carbon builds that are hard to reach. Any AR chambered for 5.56 should function with any quality ammo. I broke in my last two with hollow and soft points cause they were all that were in hand. Just cleaned and lubed prior to shooting. If your problem is persists or rears up, call S&W...

lol that you linked me to Hickock45 because he's basically the guy I used but instead of just using ballistol I like using a solvent then an oil. Ballistol works pretty good but a lot of people use my combo too and Hickock would approve of it probably. I don't have a bore snake but I used a .22 bore brush, patches, q-tips, and a toothbrush. Perhaps I need a boresnake but a rod should do pretty well if you deep clean like I do.

ok, I ran a bore brush down it, cleaned the bcg with solvent and then wiped off the excess oil, got all up in it with some solvent and a toothbrush.

30 rounds, 3 times where the bolt wouldn't fully lock into battery after a shot. Twice I had to separate the upper and lower just to get the round stuck in the chamber which seems dangerous. It is bending the casing. So it is obviously a feeding problem. Weird thing is that the last 20 rounds or so went off without a hitch (which would lend to magazine issues) but this has happened with multiple brand new magpul pmags.

I'm done dumping money in ammo trying to figure this out, I'm sending it in to S&W and letting them figure it out.

I agree, at this point call S&W and get a shipping label to send it back to them. Let them figure out the problem.

Good call.

This is proof positive that a shooter should simply NOT clean the weapon until malfunctions begin. . . .

I just called them, very courteous, they're gonna send me a label and they want a note explaining what is happening (which they'll figure out themselves).

I'm gonna spray it with the solvent and send it to them bone dry I figure. I'm gonna ask them to lube it up as they see fit and I will do the same.

well I did clean it upon getting it home from the gun store after those initial 60 rounds. That is when the problem began. Lesson learned though, rifles are not like pistols that I can easily disassemble and soak in solvent. I've shot glocks (and a cz75 p07) out of the box with grease flying out while I'm shooting and never had a problem but I ventured into AR territory for SHTF situations. I'll probably pick up an AK when I have the extra cash because of the ammo costs and they seem to be a little more reliable (with the cost of accuracy).

The above is correct. Hoppe's #9 is a solvent for bore cleaning not a lubricant. That could be part of your problem. The charts below might help.

Attached Images

	AR 15 Lube Points 01.JPG (234.7 KB, 143 views)
	AR 15 Lube Points 02.JPG (236.3 KB, 141 views)
	AR 15 Lube Points 03.JPG (131.0 KB, 122 views)

no Hoppes makes solvent and lube. If you don't believe me go to wally world or academy and look. They even sell a cheap kit for 10 bucks at wally world that has some rods, solvent, and lube.

anyway follow up: I sent it to s&w after spraying everything down in solvent and scrubbing it. That did it, after I did it twice it did the trick. They didn't find a problem and I ran 90 rounds of 3 kinds of ammo in 3 mags without any problem.

One thing I did last night cleaning it: I got a q-tip end stuck in the gas key like an idiot, but apparently it will just burn up and I got most of it out with a wooden skewer. Apparently I'm not the first person to do this and everyone on the internet that did it said they shot it and it burned the cotton up so I'm not worried about it.

Thanks for all of your suggestions and thank you S&W for taking a look at my gun. It isn't my only S&W and it won't be my last. Their customer service is awesome.

ok I'm bumping this up because after sending it in to S&W it is still having this problem. There is no residue of a q-tip in the gas key and I've blown out the gas tube. It is jamming where it bends the end of the crimp where the bullet meets the casing, to where it will not chamber fully. I'm using Independence, Federal American Eagle, and Perfecta brass ammo. All gen 2 magpul pmags (just like the one that came with the rifle). I'm cleaning the hell out of it with a .22 boresnakke, lubing the hell out of it with either Hoopes 9 oil, CLP or Remoil. Does the same stuff. I am not a happy customer right now. I'm now seeing why people bash the sportsters because at this point I'd never recommend someone else buy one.

With the bolt in the open position insert the mag and give it a good smack on the bottom to make sure it is seated properly. It sounds like the mag is not completely all the time.

Ok, slow down... Is it doing this with the first round, the 10th round, or what? Does it do it with all of your magazines at the same round? Are your magazines marked so that you are sure it is doing it with all of them, and not just one in the rotation? Also, are you making sure that the magazine is seated well by pulling on it after inserting it?

And I know you are not happy, however I have seen DD and Colt both have these types of issues as well. Anyone who "bash on the sporters" are idiots... any manufacturer can put a lemon out, and by your own story, it sounds like your rifle will shoot many rounds just fine before having an issue.

it is doing it at random times, with random magazines, with random ammo. Whenever I have a malfunction with any gun I mark the mag. When I notice a gun is not liking a certain brand of ammo I stay away from that ammo (even though a modern AR-15 should shoot anything that isn't a ****** reload and I've never even thrown steel through this one).

I tap the mags before I put them in, and make sure they are seated correctly. I've even tried putting in 28 rounds to see if it is a problem.

I'm a handgunner by hobby, but I wanted this just because I wanted an uncle sam really for SHTF situations. I am one of those people that run glocks/s&w/cz75 because I think a gun that jams at all is worthless in this day in time.

I'm getting to the point to where I feel S&W owes me money due to all the 5.56 ammo I've wasted just to function test it. That **** isn't cheap and I only give it good stuff.

It still sounds like a magazine issue to me. Next time at the range, when you get a stoppage, grab the magazine and try to rip it from the rifle. Grab it and pull down hard, making sure that it is locked into the lower... do this when inserting the magazine as well...

If you find that your magazines are not locking in, then try tightening the mag catch. If that doesn't work, the mag catch may need to be replaced. If the mags are locked in, and it does this with multiple mags and multiple ammo, you will have to send it to S&W again.

Do you have a friend with an AR-15? What I'm about to propose is stupid, but it will narrow the issue down to your upper, lower, or magazine. This works because AR-15's are built upon standardized dimensions.

1. Make sure your friend's AR-15 is in perfect working order.

2. Making sure your M&P 15 is cleaned, lubed, seat the mag with a smack, a.k.a. everything you've done so far. Verify your issue. Try not to get frustrated.

3. Clear and safe both rifles. Separate both rifle's uppers from their lowers.

4a. Mount your friend's upper to your lower.
4b. Mount your lower to your friend's upper.

While using the same factory ammo, preferably from the same production lot...
Making sure you've marked magazines to readily identify one from the other...

5a. With the rifle comprised of your friend's upper and your lower, put rounds downrange.
5b. Shoot with your magazines. Check for issues.
5c. Shoot with your friend's magazines. Check for issues.

6a. With the rifle comprised of your lower and your friend's upper, put rounds downrage.
6b. Shoot with your magazines. Check for issues.
6c. Shoot with your friend's magazines. Check for issues.

Mitigate any issues that may be marksman induced. Have said friend shoot the test.

Keep a notebook handy. Log the performance test to document the issue.

You'll quickly zero in on which portion of your rifle is suspect: Upper, Lower, Magazine.

When you call S&W, you'll have an idea of where the issues are. You can then have an informed discussion with the S&W customer rep. You will then have some knowledge to work with when you receive your rifle back from S&W with the explanation of repair.


I empathize. I used to have an extensive pistol collection. Since I earned a concealed carry license, my viewpoint on pistols have shifted to be similar to yours. Practicality and reliable function over aesthetics. In the context of a firearm who's purpose of use is to defend life and limb, any firearm that is a jam-o-matic is worthless. A firearm that requires extensive breakdown and cumbersome cleaning/maintenance to ensure proper operation at all times isn't one I choose for defensive duty.

My carry gun and primary HD pistol are Glocks. I don't have to explain to you why.

I'm an old-timer on this sub-forum. I used to own a M&P 15-Sport. I did everything possible to mitigate the disadvantages and shortcomings of the direct gas impingement system. By the time I was done and totaled the cost of parts and the time I take to maintain the firearm, I had to rethink my choice. By no means does that mean AR-15's aren't great rifles. They are. They're just not for me.

Lots of things to think about. I understand your frustration. Pay good $$$ for something that everyone says is awesome, yet yours isn't.

• Is my 15-Sport a lemon?
• Is the AR-15 truly what I want?
• Should I switch to an AK-47?
• What are my real needs?

Again, I can see how it can get frustrating fast. I can offer this tidbit from my own experience and being honest with myself.

1. I need to hit minute of bad guy on a moving target at 100 yards under less than ideal range conditions. Anything over 100 yards, consider me the best suppressive fire you can have sitting next to you.

2. I'm not a long distance marksman by any standard. I don't practice for it because I don't have the facilities nearby to practice it.

3. If the rifle happens to provide better than minute of bad guy accuracy in my hands, it's a bonus.

4. While I am more than capable of maintaining an AR-15 to the peak of performance (see my cleaning/maintenance thread in the stickies), I've learned I don't like to do it.

Have you ever given thought to a rifle that uses a different operating method to cycle the action? I've moved onto rifles with long stroke gas piston systems: IWI Tavor (5.56) and an AK-M (7.62x39). Shooting enjoyment has increased. Post range maintenance time has decreased considerably.

Goodbye:



Hello:





I'll end my rambling post here and don my flame resistant safety suit.

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-John

Yeah I completely understand what you are saying, but I've been taught by Marines/Army people now how to maintain an AR-15. Not a very painstaking task if you know what to do and are willing to spend 15 minutes. The mags run fine out of other people's AR's (my friend has an FNH) as well as the Ammo. I have not switched uppers and lowers, just because, well, in my opinion it isn't my damn job to make sure this rifle (less than a year old now) runs fine out of the box. It is also hard to say "hey my AR is a jam-o-matic, let me throw my lower onto your upper" or vice-versa. That is all on Smith and Wesson in my opinion, to make sure I'm happy with what I purchased from them. It'd be different if I was throwing reloads or anything ****** through it.

I know plenty of folks with AR-15's and a couple with sporters and they don't have this problem. So it is up to S&W to make this right, not me spending 35-50c a round to figure it out. Like I've said I've gone through enough 5.56/.223 BRASS to had not cheaped out on the sport and bought a Colt or at least a Ruger. The way I feel right now, no way I'm putting another round I paid for through it before S&W resolves it. It'd be different if it was a "once and a while" thing but this happens every time I go out there and I know it isn't a mag, ammo, or lube problem. I've seen my friend run his FN bone dry just about and run a 60rd magpul drum as fast as he could.

Yeah I'm getting to the point of buying an AK and just saying "f it" because AK's get the job done.

dude the mag is in there tight i promise. at least to the point to where it isn't wanting to fall halfway out. The only way to get the jammed round out is to take the mag out and yank on the back of the charging handle and pray that it doesn't pull a muscle to get the thing out. This rifle has caused me slight injury even. I've pulled on the mag to make sure it was in tightly before I took them out to clear the jam.

Basically **** tightening anything myself, or changing uppers/lowers, this thing is going back to S&W ASAP. I could have built one cheaper, had forward assist and dust cover, and had these screw ups and it be on me. I bought s&w because of its reputation and lifetime warranty.

I would send back the AR 15 to S&W with a brief letter of problem followed by a DVD or memory card showing you at a range with your problems. Be specific at which time this problem arose. Call them first and explain you have already sent it to them once, and who specifically what person will know you AR is going to and they are aware of your video. Ask them to fix it right, or get you a new AR.

I'm not burning a DVD for them or giving them an SD card to realize that it isn't slamming into battery and bending the casings to the point of complete dissasembly to clear it. In fact I'm not burning up another few 5.56 rds of my own either. I'm calling them tomorrow, letting them know what is up, that I'm sending in EVERY mag I've ever used for it plus the rifle.

I'm not trying to come off as snarky, because everyone has done nothing but try to help, but it is getting ridiculous at this point. I've spent money with s&w (4506, shield, mod 36) enough to where they should honor their word without me having to go back out there and shoot a film and burn it for them. I know it could possibly help them but seriously there can't be too many things causing the issue and it is pretty simple. It isn't like I could be limp-wristing or anything.

Has S&W given you trouble with warrantying your gun...?

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Jack C

no, other than it is still having this problem, after sending it to them once and them saying it was ok, using my Pmag and theirs.



unless they can explain why this is happening with every single kind of ammo I've ever ran through simply, then they need to replace the rifle or at least run it until it emulates the problem and fix said issue.

Wow... just read some of your previous posts.... sounds like your disdain for S&W can only be satisfied with owning an AK and a Glock...

Good luck sending it back..

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Jack C

I don't have much disdain for s&w other than with this particular weapon. My shield 9 didn't like a bad batch of rounds, figured that out when I ran the same rounds through my Glock 19 and M9.

Other than that (which was directly ammo related) I haven't had any problems out of S&W. My mod 36 was fine, my 4506 is great, and my shield 9 is my backup edc gun.

It is just a tad disheartening when you spend $600+ on a gun, decide to get it over a Ruger because you like S&W better as a whole, and then S&W can't figure it out after you send it in once. A well-kept AR-15 should NOT jam, I'm not in Iraq, and it definitely shouldn't be jamming every 50 rounds at least to the point of having separate the upper and lower and pull a shoulder muscle.

Oh my....... The drama and side effects are killing me..... you may have to call a lawyer for all the physical damage you incurred with your $600 gun....

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Jack C

lol so you think it is ok that s&w sells me an inferior product apparently? or that they shouldn't have caught the problem the first time around and sent it back to me with the same exact problem?

you're perpetuating just as much drama by obviously being a S&W fanboy. I DO have a problem with their warranty work obviously. Yeah I'm a tad pissed but you probably would be too.

Anyway I don't know why I got on here other than to complain, because I'm out of "suggestions" and people blaming multiple brand new PMAGs. From now on this issue is between me and the people who work for S&W.

I'm wondering if my some oddball mistake you don't have a barrel with M16 feed ramps in the barrel extension mounted in am M4 receiver. If so that may be the reason you are having problems. Good news is that this type of assembly mistake isn't very difficult to spot, all you have to do is look to see if the feed ramps machined into the upper match the feed ramps machined into the barrel extension.

So, some definitions just to insure that you look in the correct area. 1) the Upper Receiver is the aluminum upper half that the barrel and handguard are mounted to. 2) The Feed ramps are two angled grooves machined and angled into the chamber. The reason there are two feed raps is because the AR platform uses a non converging double column magazine so the bullet can feed from either side of the magazine. Note, it just occurred to me that a missing or improperly feed ram on one side could cause the intermittent failure you are experiencing, so look to see that both feed ramps match each other. 3) The Barrel Extension is a separate part that screws onto the barrel itself and the Extension is the part that features the Locking Lugs for the bolt and two separate Feed Ramps that should match the ramps machined into the receiver. If there is any mismatch then that would be a problem. Note, a very slight step or visible line is NOT a mismatch, for this discussion a mismatch is something in excess of 1/32 inch.

I'm a mechanic.... when it comes to anything mechanical... on a car or a gun for that matter... I can usually fix it or figure it out. It's not unusual to have a customer complain about a problem with their car, yet when we get it... it just won't do it... so the bottom line, unless it does it.. tough to fix it. Taking guesses gets expensive on a car... You act like SW sent you a gun back on purpose that malfunctioned... get a life..

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Jack C