I'm not sure anyone has posted this yet or how many people know this already so I figured I should post it.

I just picked up my very first AR, an M&P15OR, got it for ~$900 after tax. The rifle is beautiful and I'm just waiting till my next pay check to install the Olympic Arms FIRSH rail I got for it. Before I picked it up I noticed something weird about the serial number on it though. The serial number was 003XX, indicating an early build. I asked the guy at the store if this was a new gun or if it was used since it seemed that the serial number was very low. He said It was new and he wouldv'e been suprised if it was an early build. So I trusted him and of course picked up the rifle.

Once I got home I checked the bolt carrier and upper receiver: It has an LMT bolt carrier (proper staking) and M4 feed ramps, meaning this was a new build.

It was only after looking online at some M&P lower receiver pics that I realised the precursor letters on the serial number were SM not the regular SW. It seems that Smith has changed the letters to indicate the newer rifles.

So what does this mean? Well it really just means that if you see an M&P15 on the shelf with a low serial number don't be afraid to pick that baby up, just make sure its the new SM serial not the SW. It also seems to be that ALL M&Ps are coming with M4 feed ramps and LMT bolt carriers, not just the premium models that I had heard about earlier.

Well I thought you guys would want to know about that little bit of news.

Thanks for the info.  Now I have to go check the serial number on the one I got in early December.  It's an OCR model, $900 after tax, M4 ramps, and LMT bolt carrier (based on when it was made).  Only thing I would really change is upping the barrel steel from 4140.  Chrome lined 4140 is certainly good enough for my needs and I'm not looking to swap the barrel, but it's a want-to-have.  These rifles are great deals and I'm very pleased with mine.

Any markings on the bolt that indicate its a LMT im not sure what mine is.

FWIW any of the serial #s starting with SW that are 5XXX or above are S&W made guns, any before that  were contracted out to another maker (Stag?) and those are the ones that had the issues. The alpha prefixes change every 10,000 guns (actualy 9999).

From what i've read there is only one way to tell if its an LMT bolt carrier and thats the carrier staking. If its a horizontal staking (looks like its been hit with a flat head screw driver) then its a stag/cmt carrier. If it was staked with a MOACKS tool (sides pushed in with round pins) then its an LMT. S&W apparently only used stag/cmt and LMT carriers so it has to be one of those two.

Heres the link to a site that has pictures of all the carrier stakings from different brands: Bolt Carrier Stakings



Thats kind of what I figured, but I just wanted to let people know not to worry if they wanted to get an M&P15 but it has a low serial number. Like I said when I bought mine I was afraid it actually was an early build. It really messed me up when I was reading online about all of these S&W builds and people saying there serial numbers were like 05XXX and 65XXX but mine was 003XX.

Why not call S&W and find out the real deal about the S/N?

I've heard that the LMT's may be marked 'MP' to indicate MPI testing as well.  I'll edit after I have a chance to look tonight.

Edit: Serial number from my December vintage is SW 91xxx.  Bolt is marked 'MP' which I believe means it's an MPI tested LMT.

No real need right now, unless I have a problem. I literally just picked this rifle up and havent had a chance to fire it yet, but if I do and there is a problem I will definately call.



Hmm, thats interesting cause I just feild stripped my gun and I saw the "MP" mark on the bolt (not the carrier). I wasn't really sure what it meant. I guess that might be the real indicator of an LMT bolt and carrier.

Both of my LMT rifles have MP on one side of the bolt and 2 letters on the other side (lot number) Hope that helps.

Curious if anyone knows who (if not S&W) makes the 5.45x39 bolt assembly. I would assume that the carrier is the same as the one used in the 5.56 version, but obviously the bolt is different.  My M&P15R gas key is staked like the LMTs, and the bolt is stamped 5.45x39 - didn't pull the whole thing apart to see if there are any other stamped markings, so don't know if it's stamped 'MP'.

I just picked up my M&P15X and it's a SM014XX, the feedramps are M4, and the BCG is LMT.

Hi,

I also picked up a brand new M&P 15OR a week and a half ago, serial number SM 0022x.  It was ALMOST the magic serial number 00223 but not quite.

Enjoy your new SM serial numbered M&P15.  It is indeed from the new batch of serial numbers for the current year!

I popped on an extra Bushnell Holosight and have had fun with it already at the range.  Zero problems.  I just got a new Magpul MOE handguard for it but haven't put it on yet, though the Magpul MOE will fit the S&W with the tall gasblock.  

So . . . the fun begins, slowly turning this SUR (Sport Utility Rifle) into exactly what I want it to be.  I'm sure you'll enjoy yours too!

http://216.77.188.54/coDataImages/p/Groups/363/363373/folders/277718/2385408SWright-e.jpg

If the alpha prefix changes every 10,000 guns why is mine SW 534xx––––-don't you mean every 100,000––-well after SW 99999

It always makes me happy to see other m&p15 owners very satisfied with their rifles. I'm going over to eastern Washington soon and I'll be taking my new "little friend" with me, so I'll be able to get a feel for it. I can't wait to finish this build. I'm planning on a tangodown pistol grip, caa CBS stock, and magpul mbus (whenever they come out) in the near future.

my M&P 15X is serial # SW 40XXX. i called Smith & Wesson today to verify birthday. November of 08, i bought it new in december of 08. I asked if there was a certain serial # that would be the begining of the in house builds and was told they didn't have that info ???

Its really not that hard to find out. Like I said the easiest way to tell is by the carrier staking. If it was done with a MOACKS tool then it was made in house. I was actually reading an article yesterday in S&W magazine (I didn't even know that mag existed!) where they were talking about their M&P15 rifles, with some nice pics of the factory. Anyways, they said that S&W actually does their own staking, which is interesting cause I just figured they got the bolt carriers from LMT prebuilt already staked.

Your right, I was tired when I responded and this is info I rececived from the CS Supervisor at S&W. They have this info but they get so pounded with calls it's probably easier to say no! Best indicator to know if you have a S&W in house gun is whether or not it accepts PMAGS!  I also belive they are making everything in house including the bolt and entire carrier group. The MP stamp just shows it has been tested. The whole reason they went to building everything in house was for QC issues and to keep costs down, they have the capability to make every part in house and do a lot of contract work for other companies. Whether that includes AR's or AR related parts, who knows but it wouldn't surprise me.

Congrats on your S&W M&P15!

I just bought mine recently, and posted a similar question in regards to the SM/SW in front of the s/n.

I also have a SM003xx, we have brother rifles
Except i'm in TX, and yours in the batch of 99 is in WA!


Can't wait to get out and shoot mine, no time lately

Plus i still need optics.....

I put an M&P15OR on layaway this morning.  I went to purchase it but saw the low serial number and wanted to verify it was an in-house build before I purchased.

Ser# is SM083xx, from what I read in this thread the SM would indicate it's a new build, correct?

I also pulled the bolt while I was looking over the rifle and it is staked like properly like the LMI picks in the linked thread.

If I can verify it's an in-house build, I'll drive back over this evening and pick it up.

I thought the change from Stag production to "in house" S&W production took place around the 50,000 mark (a guestimate posted on arfcom previously) but you are saying S&W told you SW serial numbers after 5,000 were "in house" builds?

I see you corrected your error between 10,000 and 100,000 regarding the serial change from SW to SM, are you sticking with your other number as well?

Got an MP15T S&W build...

It's just amazing. I don't know what convinced me to go out and buy so many piston rifles after owning this one and experiencing ZERO problems.

I should have just purchased a couple more of these beauties before they became so friggin' rare.

RE:  Best indicator to know if you have a S&W in house gun is whether or not it accepts PMAGS!

OK, do tell.  I just picked up #SM 076XX today (Gander Mountain for $1198) and I am shopping for mags.  Are you saying that the new builds take pmags and the old ones don't, or vice versa?  I'd hate to buy 10 paperweights right out of the gate...

Only the old ones (SW 05XXX and lower) don't accept the PMAGs, so if you have the newer SM serial number you CAN use the PMAGS.

If I am reading this correctly, the sm24xxx serial number on the rifle I am thinking about getting is an in house model. This will be my first AR and don't want to get into problems right out of the gate.

My M&P 15, made by STAG  (SW07210), takes pmags just fine.  David

Yes, ALL prefix SM serial numbers are late model production built "in house" by S&W. In the beginning of S&W offering M&P-15 rifles, they had them built under contract by Stag and those serial numbers have a SW prefix and a serial number under 50,000.



I have one of the early examples and it is still a great carbine; takes PMags and is 100% reliable.

I also have the newer "in house" production version which has the different BCG and of course I'm happy with it as well.








 

The M&P15's that are made "in house" get they're BCG from Thompson Center.  S&W owns it.