heres my new baby....bought it from a guy at a local gunshow....

a Model M&P15...... and ive had it out a few times shooting .223's and was wondering if i was capable of shooting 5.56NATO and i wouldnt have a problem except.....
theres no caliber stamp on the barrel......ANYWHERE


now i saw that most of the M&P15's on their website show 5.56 but im hesitant(as i should be) to try a couple 5.56 rounds.... so until i find out its strictly .223 for me

any help on finding out this information would be greatly appreciated.... thanx guys!

I don't recall Smith making a 223, there had to be a stamp somewhere.
Receiver, under the hand guard, possibly covered by the gas block ????
I'm not sure in that particular barrel.

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Light, Accurate,Versatile M&P

The problem here is you have no idea if that barrel is the stock barrel that came with the gun. With the AR being such a modular system, when you buy used, you can't be 100% sure that all parts are original.

If you can't find a marking on the barrel indicating what it is chambered for, I would take it to a gunsmith just to be sure.

Looks like an OR model with a carry handle and front sight added, but that gas block doesn't look stock....

That doesnt look like any M&P15 upper I have ever seen, could the upper be a homebuilt put on a M&P lower?

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Grover Oathkeeper

the upper is identical to my father in laws M&P and the barrel is exactly the same right down to the factory flash hider, just his is stamped.. and hes got a bill of sale from gander for his

the gas block looks like one ive seen on cheaperthandirt.com made by J&T Distributing but functions nicely plus the picatinny rail is nice to have down the road a bit

i checked under the hand guard numerous times
the gun it self is smooth as butter and shoots .223's nicely all day long... so im not really concerned if it is going to be reliable for me but is there anyways i can contact someone at S&W or is there any numbers on the upper anywhere that will tell me that my upper really is a S&W Upper... the guy i bought it off of said its all original from when he bought it so i dont know... again.. any help is greatly appreciated

Most of the barrels look pretty much identical from just about all manufacturers. Can you tell me if that front gas block is on the same plane as the upper receiver, or is it a little lower than the upper receiver rail?

Every smith that I know of has the 5.56 and barrel twist stamped on the barrel near the muzzle. I've seen several after market barrels that are not stamped, and I'd like to know where they are marked as well. I'd think there would have to be some identification on it somewhere.

Is your gas block pinned, or is it secured with allen screw from the bottom? I asked about the height of the gas block as Smith only used same plane gas blocks, but there are several after market uppers that come with a lower gas block, utilizing a front sight made for the lower gas block to get the right sight height. Why they made two different heights, I have no idea.

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Rod
M&P 22A, 40c, 15A, 15-22

i think you're right on this one
heres the factory stock photo for the OR



that looks identical for my gun when i have the carry handle and front sight off but the gas block definately isnt stock.... so confused.... oh well still a blast to shoot guess ill have to run down to the local gunsmith and have him look it over on actual caliber... hopefully next week ill get some magpul goodies at the next gunshow... i wanna do a vertical grip and a tactical light with a red dot of some type...

It's also entirely possible that you have one of the first M&P's that smith put out, and at that time, they didn't build them in house like they do now, which could explain why no barrel markings.

Although I have no idea if while they had the uppers built else where, that they were or weren't stamped as they are now.

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Rod
M&P 22A, 40c, 15A, 15-22

a little lower plane and its set in place with set screws from the bottom.....grrr.. oh well like i said... still shoots well and i love the hell out of it

You may be right crracer...I have heard that Stag Arms used to make a lot of the parts when S&W first got into the AR game.

Have a competent gunsmith measure the leade (chamber length). The 5.56 is longer to handle higher pressures.

I think you will find it is a 5.56 chamber as most 16" bbl.s have.

S&W builds a couple of longer bbl'd rifles in the "custom shop" but those have longer bbl.s and are specialty items.

yeah the Delta ring to handguard size is different also, but if it runs sweet and you enjoy it, Welcome to the club, We aint prejudiced. Some of the smith models say they will shoot .223 and 5.56x45, as far as I know the sport is the only one that in the advertising paperwork says it is chambered for 5.56x45 without adding the .223 but I think that is just an advertising ploy. Enjoy and let us know how things are going.

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Grover Oathkeeper

My Sport says S&W on the collapsible buttstock. Do they all? I noticed that his Buttstock is different than my sport but that doesnt mean anything either. Just wondering.

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Grover Oathkeeper

I wonder if you'd take a look at your BCG, take it out and extend the bolt and see if there is a letter stamped on it behind the grooves.

Nothing wrong at all with what you got, no matter what it is. Smith has sold the lowers only and it's entirely possible someone used their lower and built a rifle. That's the fascination with these rifles, at least for me, is the vast amount of parts and it's all interchangable.

There's nothing wrong with the gas block being on a lower plane, they've made front sights for as long as they've made these rifles, to accomodate the two different heights. I just wish I knew why they made two different heights to begin with. I have a DPMS upper that has the lower style front gas block, just like yours.

The nice thing about your gas block, should you be inclined to change it, it's a breeze to change compared to the pinned gas blocks.

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Rod
M&P 22A, 40c, 15A, 15-22

My 15A has the S&W logo stamped in the butt stock as well. My new 300 whisper does not.

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Rod
M&P 22A, 40c, 15A, 15-22

I find it interesting that you have a carry handle on a rifle without a fixed front sight. Definitely puts it in the "Franken Upper" category for me. I think I would want to identify the components, just to know what I have.

Still, the liklihood it isn't 5.56 is pretty low, IMO. Best bet is still to measure the leade to be sure before firing 5.56 with it. You should be able to see if the bolt is chromed (lined) and also the bbl.

Early S&W lowers were stamped 5.56 but this would mean little with a put together upper of unknown origin.

At first glance, your rifle looks identical to mine, an MP-15 Model 81100 with the carry handle fixed rear sights. After looking closer, I can see your gas block is different with no bayonet lug on the bottom of the GB, nor sling swivel between the fore guard and the GB, but barrel looks the same. Mine has "556 NATO 1/9" stamped on the top forward section o the barrel just before the flash suppressor.