ok guys, got a question, im pretty sure i know the answer to but i wanted some reassurance. while working today i happened to pass a store and a smith and wesson dealer sign caught my eye, so i stopped to see if they had any 223 in stock, well they guy says sure here ya go, and hands me boxes that say 556, and i said oh no good i got a 223, you cant shoot 556 out of it. so he asked me what kind of gun, m&p15 i said. so he says its a 556, i told him it says 223 right on the barrel not 223/556, he said i think your wrong, i knew i was right, and he said either way ALL smiths are chambered for 556 so you can shoot 556 no matter what the barrel says.... now i think thats dead wrong, if it could handle 556 it would say 556, am i wrong? my gun says 223? if this guy was wrong he definatly is giving info to people that could be potentially dangerous?

Your owners manual should have the answer for you

All S&W M&P15's will shoot 5.56 and .223. I didnt know that some were just labeled .223. all of them I have seen are labeled 5.56 and some are labeled 5.56/223 but if you have one that only says .223 I would ask. Did you purchase the rifle new? There have been threads in the past that have asked this question. But all Smith and Wesson M&P15's are chambered for 5.56.

If yours is labeled .223 then you dont have a S&W Barrel, and I am back to the question. Did you purchase it new?

Look at this thread:
http://smith-wessonforum.com/smith-w...-223-only.html

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Grover Oathkeeper

I've never see a M&P in .223. If your barrel is truly marked .223, I'd bet the gun was bought used. S&W sold/sells lowers.

If your barrel is stamped .223, then I think you're being justifiably cautious. Did you purchase the rifle as a new complete factory rifle? If so, then I highly suggest calling S&W Customer service. Provide them your serial number, and they should be able to tell you what model M&P 15 you have. WIth the model number, you can find out for sure the chambering of your rifle.

I'm pretty confident that all M&P 15 rifles are chambered in 5.56.

If you purchased your rifle used, then it may be a little more difficult to determine. The rifle could have been built around a stripped M&P lower. The previous owner could have replaced the barrel.

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-John

i did get it used, but from a friend, according to him he bought it new the way it is

been doing some research and i found this, this is the actual model i have and it says 223 only
http://www.smith-wesson.com/webapp/w...layErrorView_Y

He must of bought the lower new the way it is. Can you provide us a picture?

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Grover Oathkeeper

If that is the model you own, then it is .223 only.


Sent from my iPhone 4S using Tapatalk

wow my apologies, that is one I have never seen...I do apologize. Yep .223 only, that is a rare bird!!

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Grover Oathkeeper

i was kinda hoping you guys were right and the dealer, much easier to just grab any 556 223 ammo, but ive been taking notice when buying seo ill just have to keep my eyes open

now can i reload 556 brass to 223?

Though I have seen plenty saying how similar they are nobody has ever said if they were truly interchangeable. Apparently they are not.

Good thing you did your research and found out you are right. Better to be safe than sorry.

I have one for you. I have a 181 series Mini-14 that says .223 stamped on the back of the reciever. I just found my old Mini manual along with some other old manuals while digging for re-loading info. In the owners manual,it says it will shoot 5.56 or.223. ??? I did call them and ask about it and they said mine was good for both and also asked how it was holding up along with it's serial number. Long story short,he said I got lucky and had one of the better ones and NOT to get rid of it.

yes, you can load 5.56 brass to .223 specs, in fact, I have not seen a loading manual with 5.56 load data so I think .223 will be your only choice

Wow. I just learned something new. I didn't know of the .223 chambered M&P 15.

That's what I do.

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-John

The reloading manual should have that info in it. Or look for manuals that do cover it. If I remember right (and I could be wrong),you might want to stay under 3200 fps. But do your research first. I'm "old school" and could be wrong. I'm sure some one will pop in with some better answers and help.

There also is a great re-loading section in this forum that would be more than happy to help you get on the right track.

Good luck and stay safe.

Not sure,but I think they "might" have been some of the really early models ???.

I use to look at the S&W AR site now and then while "shopping" around for new M&P handguns. I noticed just by chance,some of the M&P AR's listed as .223 on some models in the past and didn't think too much about it. Then a couple of AR members in here,pulled me over to the "dark side" and now I have the FULL BLOWN M&P addiction with no cure in sight. I love the smell of hot melinite...

You will need to remove the military crimp from the primer pocket though. RCBS, Hornady etc make a tool specifically designed to do this. Otherwise you are good to go!

a primer pocket reamer will remove the military crimp, I do it all the time.

Kurac the latest Hornady manual has 5.56 and .223 data in it. There is a small difference in max loads, but a difference none the less.

As long as you load your rounds to magazine length and follow .223 loading data you should be good to go.

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Grover Oathkeeper

The Nosler manuals have a different area for both the 5.56 and the .223 rem. .

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15T,15-22,5946 & some not S&W

nymike,

Is this the rifle that you struggled to get the barrel nut loose on, finally machined it off? You thought it had been pinned, did you determine that to be true? The upper would have some hole drilled in it, probably in the threads. Just curious. Wondering if S&W went that extra step to insure that model was compliant and could't be readily changed. That might explain the 223 barrel. Also, what FF did you install?

yes same gun, reasons could all be linked

My understanding is that the .233 and the 5.56 are basically the same with a few exceptions from the "sporting" .223 to the "military" 5.56.

-the leade (throat) space is longer (SAMMI specs) on 5.56 to accommodate a longer OAL sometimes found in military 5.56 ammo.
-the brass on a 5.56 is slightly thicker than on a .223 thus the variations you will see in loading data.

I would be wary of firing 5.56 ammo in a .223 because of the risk of running a bullet up against the rifling in the barrel...not good! BUT, having said that you can find lots of info stating that you can fire either in a .223...I'm not sure I would do it as the 5.56 ammo will run at a higher pressure in the true .233 from lack of head space and leade.

now can i reload 556 brass to 223?
That should be fine but I wouldn't load .223 to 5.56!

Most AR type rifles are chambered to handle both but when in doubt a phone call to the manufacturer is needed to be sure.

I load .223 brass to 5.56 data all the time...on the powder I use the difference is .1gr. No pressure signs no problems with the brass and some of it is on its 4th and 5th reload with no problems.

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Grover Oathkeeper

To my understanding, the OAL. as listed by SAAMI for both the 5.56 nato and the .223 rem. is 2.260. The reasoning for the different leade is with the thicker casing in the 5.56, the case volume is reduced. This causes a higher starting pressure. The leade is slightly, just slightly longer in a barrel chambered for 5.56 to give the bullet alittle more time(microseconds) before it contacts the rifling of the bore. This gives the pressure time to drop down some. As far as the headspacing is concerned, there is no difference between the two. The case dimensions are the same exact. These rounds headspace on the shoulder of the case. I hope this is useful information for you.

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15T,15-22,5946 & some not S&W

Take it to a gunsmith and have him run a 5.56 chamber reamer in it and you are good to go.

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CSM, U S Army(Ret) 1963-1990

You probably have a "compliant" rifle, and I understand those are marked for .223 to avoid the whole "military cartridge" thing that seems to cause so much heartburn among certain types of people.

The real question then, is whether S&W actually chambers all rifles the same, and just marks the compliant ones differently; or, whether they really are chambered differently. S&W will probably tell you to shoot only that ammo for which it is chambered as marked on the barrel.

The reason for this is that there are differences in the dimensions of the chambers of the 5.56 and the .223. I believe the general rule is that you can shoot both in a 5.56 chamber and only .223 in a .223 chamber. I recall an article years ago, however, in which Ruger (maybe Bill Ruger himself) was bragging (and justifiably so) about the strength of his Mini-14, and he said that the Mini-14 would handle the 5.56, no problem.

That said, I would follow S&W's advice. Your only other option is to take it to a VERY reputable gunsmith and have the chamber checked to be sure of what dimensions you have in your rifle. Short of that, use the ammo shown on the barrel.