My M&P : Chambered in .223, will it take 5.56?

[Hostile Amish]

What with the economy going to hell, among some other things I won't go into here, I see the need to cut back a little on ammunition expenses. I have heard about the dangers about firing .223 in a 5.56 - designed weapon. But would 5.56 work in a .223? Specifically, the Smith and Wesson M&P15OR rifle. The Smith and Wesson website says that the rifle is chambered for .223/5.56, but will firing cheaper 5.56 do any damage to my rifle, or shorten the life of the parts?

 

[Deus Machina]

There's no danger in firing .223 in a 5.56-chambered rifle. The danger is firing the slightly larger and higher-pressure 5.56 in a gun built for .223.

I'm not sure about the M&P specifically, but I would say if S&W labels it as a .223/5.56, either is kosher.

 

[WarHall]

The M&P

Has a 5.56 barrel - It is, in fact, made to fire 5.56 rounds in SAAMI spec and is NOT a .223, although it will shoot them. There is plenty of info on this everywhere...

 

[45B@cav]

It is fine. The .223 will shoot all day in a 5.56 chamber. I would not fire 5.56 in a .223 chamber. If you are really concerned contact S&W and they will let you know.

 

[JImbothefiveth]

Like others have said, it's actually the 5.56 that shouldn't be fired in a .223 chamber, but .223 in 5.56 is fine.

 

[taliv]

It is, in fact, made to fire 5.56 rounds in SAAMI spec

got a link to that 5.56 SAAMI spec?

but will firing cheaper 5.56 do any damage

where are you finding 5.56 cheaper than 223?

The danger is firing the slightly larger and higher-pressure

higher pressure? yes
larger? no

 

[WNC Seabee]

The barrel on my S&W M&P15OR is clearly stamped "5.56 NATO"

 

[jackdanson]

I fire both through mine, I've never had any issues at all.

 

[possum]

check out this website.
http://ammo.ar15.com/ammo/

the m&p should be 5.56 you will be fine shooting .223 in the 5.56 but not the other way around.

 

[Mr. T]

M&P: Chambered in .223, will it take 5.56?

I happen to own a Bushmaster AR-15 and they go into specific information about this topic. You can fire .223 ammunition out of a 5.56mm weapon without a problem, but you can not fire 5.56 ammunition out of a .223 caliber weapon that is specifically stated as a .223 only weapon. Bushmaster is calibrated to fire both and as such on the barrel of each weapon they have 5.56 NATO stamped on the end of the barrel near the flash suppressor. Maybe your M&P has the same thing? If the manufacturer states that the gun can handle both types of ammunition, then it must be rock solid information. If it is only chambered for .223 they would have to state that. In this litigous society, the lawyers would have a field day with a manufacturer that neglected to tell its customers about a problem as serious as that. If your still not sure call the customer service department at Smith and Wesson and they will undoubtedly be able to tell you. If you see .223/5.56 stamped anywhere on the weapon though, it will safely fire both types of ammunition.

 

[SaxonPig]

Gosh, I've been shooting military 5.56 in my .223 rifle for years.

Higher pressure? Nope. Slight case dimension difference? Yup (shoulder is a hair farther forward). Still within manufacturing tolerances? Seems to be.

But maybe I'm kooky.

 

[Lloyd Smale]

it doesnt matter squat either way. 223 chambers are a little tighter and may cause funtioning problems with some military ammo but if it will run it sure wont hurt your gun. Id sure like to hear a common sense argument otherwise. there the same gun other then a slightly tighter chamber on the .223.

 

[TexasRifleman]

But maybe I'm kooky.

Lots of people do it.

SAAMI however continues to recommend against it so......

 

[heron]

I started wondering about this after I got my .223 Saiga. I called the gun shop where I bought it, and the guy there (who seems pretty knowledgeable) said it won't hurt to use the 5.56. He did state that it could be a problem in some older weapons, but that any new gun should be okay. I've used both; no problems, although I will only buy .223 ammunition in the future.

 

[proven]

i would read these before you make your decision based on what "some guy" tells you.


http://www.saami.org/Unsafe_Combinations.cfm
http://www.hornadyle.com/faq/index.php?qIdx=3
http://le.atk.com/pdf/223VS556.pdf

 

[possum]

there are not many people at any gun shop that i know of that i would take there word. I woudl cross reference, jump on here ask you guys, ask my dad, etc.