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Discussion Starter #1
Fired subject gift from wife over the weekend. New purchase from dealer. If there are any viewers with same, then check your fired casings for damage.

Rifle loaded, chambered, fired, and ejected as expected, with no indication fo problems. 5.45x39mm rounds are all Russian made (steel case, berdan primers). Shot 12 rounds (NIB, Wolf, non-corrosive, 3.45x39mm, 60gr hp); first ammo it ever fired by a customer owner. Way too cold for more, so I habitually pocketed spent casings, cased it, and planned to clean it after getting back home the day after. While walking the dog, felt the spent casings and gave them a quick look. 9 of the 12 casings were severely expanded at the bottleneck, 1 had a large split in the neck, and 2 had shiny finish at neck where bottleneck starts.

Immediately contacted S&W, and told to send it back for evaluation.

Barrel stamped 5.45x39mm, and other box markings said same. S&W phone tech confirmed SN matched 5.45x39mm as well.

I left as is, and sending back as soon as box arrives from S&W.

Casings gave the appearance of fire-forming to a longer casing. This can't happen if chamber is cut to 5.45x39mm dimensions, and using correct ammo; and if shell doesn't seat with closed bolt, then it isn't supposed to fire (that's what the forward assist is for). M&P 15 is typically a 5.56x45mm round (M-16 round). Fire-formed appearance looked eerily similar to what a 45mm casing would be. I'm guessing the barrel was correctly cut to 5.45mm (saw no barrel damage), but chamber somehow cut to 45mm vice 35 mm. Loaded OAL of both cartridges is nearly identical, so, the bullet of a 5.45 round in 45mm chamber would meet barrel at about the same point. I may never know from S&W what they find, but figured this forum might be interested in the information if others have this new rifle (only been out a very very short while).

My thoughts are that since it shot well, with no loading or cycling problems, then other owners may not notice the problem because the casings are not reloadable. Were I not in the habit of policing my casings, I'd have probably left them where they lay, and been oblivious to the problem.

If I'm correct about the reason for the problem, then it certainly won't be confined to just one barrel. First thoughts might imply that it isn't a major safety problem, but extended firing without knowledge of the problem may set up situation for significant failure (i.e. portion of separated case lodges in barrel and sets stage for obstruction explosion).

When I get resolution, I'll let the board know what I'm told. My suspicions may prove wrong, if somehow maybe the firings took place when bolt wasn't fully closed. Rifle has not been disassembled, but checked for proper functioning and no obstructions prior to firing.
 

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My first M&P15 had some serious issues. Mine was a 5.56 Nato though. The factory had the barrel nut loose, gas tube canted in the reciever, and the carrier key was loose and not staked properly. I didnt even fool with S&W with it, I just sent mine to an Armorer in Northern Virginia that works on Military Weapons.

So dont be surprised if it does have problems. My 2nd one, was an M&P15A, and it was flawless, and the carrier key staking problems had been fixed too.
 

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Check over on AR15.com. A guy over there had the exact same thing. It took forever for S&W to replace his upper and I cannot recall exactly what they said the problem was; I think they said it was short chambered for the 6.8 then finished in 5.45. x39 but that doesn't make any since. What I think it was was that S&W short chambered the barrel for 5.56 then finish chambered it for 5.45 x 39. His would not chamber a 5.56 round stopping just short of locking up which made me think it had been short chambered for that round then finished with the 5.45 x 39 reamer.
I searched and searched for the thread but cannot find it. I think it is about 6 months old but the search only goes back 3 months and the archives didn't turn up anything.

I was working at a gun shop when the M&P 15 first came out. Eleven out of the 12 we got in had to be returned for front sight issues and with this chamber problem I have sworn off S&W ARs. Anyone who lets mischambered rifles out the door is not paying very close attention to QC.
 

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Discussion Starter #4
I haven't found it on that board either. Will spend some quality time there later. I'd have probably passed this rifle up, but it was a gift, so, you know how that goes. Will have to follow through with S&W, and when they says it's good, it's off to a quality gunsmith for the real truth. When it's perfect, then I'll build it up always for what ever numbers flow after the current 38 years of marriage.

I'm still convinced that the barrel is correctly cut to 5.45, but don't want to do any measuring before S&W gets it (no stray scratches for silly S&W implications). I also can't believe that the firing mechanism is allowing the bullet to fire before the bolt is fully closed; I couldn't believe that anyway or with 12 shots I should have had a bullet bouncing around the chamber. One other thing I didn't mention is that my first three shots were mostly accurate, then my grandson shot nine times, and the accuracy was awful; that makes me think that maybe the barrel isn't cut to 5.45. Curosity is killing me, but I'm of the belief that S&W gets to make it right first.

I'm tempted to measure the chamber cut because it simply has to be cut to 45mm length and 5.56 case dimensions. I'll certainly post what S&W tells me, if anything.
 

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S&w M15

I have one, but 5.56 NATO...The problem I am having it seems the bolt seems to have unusual wear patterns on it. My friend has a DPMS wear is very smooth, both have fired the same amount of rounds. No on ever bothered to give me a reply back...
 

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Discussion Starter #6
I have no history on bolt wear because I've only fired 12 rounds. Still waiting on S&W to get back to me on what the problem was, and what they'll do to make it right.
 

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Discussion Starter #7
Received the M&P-15R back from S&W today. Included note simply stated that "..The following characteristic(s) have been examined and adjusted to our standards...REPAIRED: REPLACE BBL."

I'll see if I can get someone to tell me exactly what the problem was, but I don't expect any details of what was out of standard. Obviously, the original barrel could not be repaired, and it only had 12 shots through it. My feeling is that the chamber was cut to about 45mm, the case size of the 5.56mm barrel, instead of 39mm for the 5.45mm round.

It will be a while before I can shoot it. Guess I need to check the chamber length of the new barrel. Naaaw, that couldn't happen twice. Yeah, Right!
 

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Discussion Starter #8
Talked to S&W today. Customer service said that repair tracking system contained no remarks concerning what the original problem was, only that it was corrected with a barrel replacement. Asked if I could speak with the technician so that I could learn what the problem was, that I can add that item to my list of procedures to review prior to firing a new rifle. No access to gunsmith technicians permitted.
 

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AR(ussian)-15s

Lion I think you're right on the money...Sounds like your rifle was chambered for 5.56x45. The brass for the 39mm case was trying, and failing, to fireform to the longer case. I went down and bought a Bushmaster Patrol M-4 last week and it is a very well made rifle. Shoots like a dream...digsests near any ammo on the range and I hade settled on a steady round of 55 gr 5.56 by the end of the range time. I don't trust S&W, or any other company who depends on over educated and undersmart engineers to design their gear. Sorta like Ruger who now seems to be run by engineers and lawyers.
 

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Discussion Starter #10
Spend time at the range with the new barrel. No problems! Rifle performed flawlessly. Smell from original problem was awful, and I thought it was the Wolf ammo. Smell with new barrel was normal. I'm now convinced that original barrel was 5.56x45 bore and chamber, just stamped wrong, and the smell was result of powder detonating in the chamber after the short cases expanded.

This one is a shooter too. After sighting in the scope, if I were a bit steadier would have been one jagged hole, out to 50 yards (length of range). No key-holes, with Wolf or corrosive Russian from 1982.

Was worried about cleanup after corrosive ammo, but I see nothing to be concerned about at this point. Heard a few horror stories, and one really bad one on AR15.com where rusted bad within hours of shooting. Ran hot water through it, dried, cleaned, CLP'd overnight, and thorough cleaning. No evidence of anything negative. I think one very key aspect after firing corrosive is firing several non-corrosive rounds at the end.
 
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