How to tell if your M&P Sport is old barrel or new barrel

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PlainsDrifter

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Is there a definitive source such a Serial Number database where you can look up your M&P15 Sport's serial number to see if it has the original 5:R or the new SAAMI 6-groove barrel?
 
The barrel is marked with the caliber and twist rate. The older M&P 15-Sports (at least mine) are marked toward the front of the barrel "5.56 NATO 1/85R". That's the best way to identify the barrel specs when buying a brand new rifle from a reputable firearms dealer.

When buying a used rifle, a serial number check will only tell you the rifle's configuration when it left the factory. Given the modularity of the AR-15 platform, checking the barrel markings, shining a bore light down the bore, and visually confirming the 5 lands opposite 5 grooves is the only definitive way to know.

I know people who've Frankenstein-ed a 15-Sport parts to different set ups. M&P 15-Sport lowers mated to full featured uppers. 1:8 5R barrels transplanted to new rifle builds, etc...
 
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Agree with JaPes... Barrel markings and physical inspection is the only way to know for sure. Only the lower is serial numbered and if you are buying used, you need to make sure that you know what you are getting.
 
The barrel on my October 2013 purchased Sport is marked "5.56 1/9". As JaPes said, uppers and other parts such as stocks can be changed very easily, so the SN on the lower doesn't really indicate any production change, such as with S&W revolvers. For example, a model 10-6 and a model 10-8 have some parts that will not interchange even though they are both model 10 fixed sight .38 special 4 inch revolvers
 
I bought my Sport in Jan of last year and it has the 1:8 5R barrel. S&W changed over sometime later on in 2013
 
6 groove M&P barrel

A friend of mine just bought an M&P 15 rifle but I looked and it does have a 6 groove bore. But is it melonite lined or is it chrome lined or not coated with anything?
 
copterdoc said:
A friend of mine just bought an M&P 15 rifle but I looked and it does have a 6 groove bore. But is it melonite lined or is it chrome lined or not coated with anything?
Click to expand...

Which M&P rifle did he purchase? Different models have different barrel treatments.
 
The older ones had a metal rear sight. The same one that comes on the M&P15-22. Thee new M&P 15 Sport has a Magpul rear sight.
There could be some over lap, but I didn't see any when I researched the rifle. As already stated, reading the barrel is the only way to be sure.
 
It says, Model M&P 15 on the side of the receiver. And it has MBUS on the side of the rear sight. Looks like it's plastic.
 
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CC83 said:
The older ones had a metal rear sight. The same one that comes on the M&P15-22. Thee new M&P 15 Sport has a Magpul rear sight.
There could be some over lap, but I didn't see any when I researched the rifle. As already stated, reading the barrel is the only way to be sure.
Click to expand...

The 1:8 twist barrel was still available when Smith changed from the LMT style sight to the Magpul rear sight.
 
copterdoc said:
It says, Model M&P 15 on the side of the receiver. And it has MBUS on the side of the rear sight. Looks like it's plastic.
Click to expand...

Still not enough info. Does the rifle have forward assist and a dust cover? If not, it is a Sport and the barrel is melonite treated.

If it does have the forward assist and dust cover, then the barrel is chrome plated.

The above is only valid if the rifle was purchased new, and no changes had been made from the factory.
 
Does it have a forward assist or dust cover? the sport is the only rifle that comes from the factory with a mbus rear sight and a 1/9 barrel. A picture of the rifle or product# off of the box would help.If you do find out which model it is here's a heads up. The TS,X,15(carry handle),OR, ORC,PS,and PSX all have chromed barrels. The MM,VTACll,300,T,and sport are melonite. The two performance center models have stainless steel barrels. S&W does advertise melonite on the new 1/9 sport barrel.
 
Bought brand new. No fwd assist. No dust cover. Model M&P on the box. Purchased one month ago.
 
copterdoc said:
Bought brand new. No fwd assist. No dust cover. Model M&P on the box. Purchased one month ago.
Click to expand...

That is a M&P 15 Sport. The barrel is Melonite treated, inside and out. S&W now calls the treatment "MCR, or maximum corrosion resistant" because Melonite is trademarked, but it is the same process.
 
So the rifling does not have the corners cut as in the 5R rifling. I think it is 65 degrees.
It has 6 standard 90 degree grooves and lands,just melonite coated. Thank you guys for your help.
 
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