223vs556 HELPPPPP

[rab]

I have just purchased my first 223,it is a smith&wesson m&p flat-top.After I ordered some ammo I got to reading that I could have some problems with 556 in my 223.I thought that 223 and 556 was the same size. the ammo was from cheaper that dirt,the add said slashed prices on 223 futher on in the add it said the ammo was 556.I sure could use some help here for I want to stay safe and not damage my gun

Thanks

[gregintenn]

They'll work. Wait....check your owner's manual....if it specifically states NOT to use 5.56 ammo in the gun, don't. Otherwise, fire away.

[Garufa]

You can use .223 in a 5.56 but NOT 5.56 in a .223.

5.56 is loaded to a much higher pressure than .223.

I don't know much about the S&W's. What does the receiver and/or manual say?

[gregintenn]

Product: Model M&P15 Rifle

From the Smith and Wesson website: "Caliber: 5.56 mm NATO / .223"

[Mike.357]

you should send the gun to me for further safety testing

[Guest last1is4me]

Its not really the pressure difference that is the problem. The 5.56 nato rounds are slightly longer than the .223. Because of this the bullet can actually enter into the rifling on the barrell instead of just being in the chamber. Some .223 chambered ar's are still longer enough to accept the longer bullet, but which ones I dont know. Read the following article I found on this subject.

.223 Remington vs. 5.56x45--Chambering and Throat Considerations

Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.

Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington? The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."

[Guest PatriotCSA]

Best gun friend of mine has an MP-15T which is 5.56 chambered. There are many different models of MP-15. You'll need to find out which one you have. There are some .223 models.

[Guest mac_05evo]

Look on the barrel and see if there are any markings.

[Reservoir Dog]

On most AR-style rifles, the chambering should be stamped on the barrel near the muzzle.

Edit: Beaten again!!

[rab]

I would like to thank all of you for the quick respones.I ckeck my manaul,it shows the cal # by the bolt lock but on the gun there is no caliber stamp just the sn#.I did find a nato 556 mark on the barrel so I hope that means 556ammo is ok, when I purchased the gun I was told it was a 223.

Again thank for the information

[Reservoir Dog]

I did find a nato 556 mark on the barrel so I hope that means 556ammo is ok,...

You are good to go with 5.56 spec ammo. Go by what is stamped on the barrel. Ignore what is on the receiver.

[frankmako]

You can use .223 in a 5.56 but NOT 5.56 in a .223. It is a case size thing. The 5.56 case is some what bigger in the neck/shoulder area. Not much, but just enough to matter. Check your gun it should say 5.56 somewhere. Or call S&W and have them check for you.

[Guest clownsdd]

'member what "thought" did....little boy thought he had to fart and **** all over himself....KNOW before you act.

[

[Guest ls2tiger]

My S&W MP15 was sold to me the same way. The owner said it was chambered .223 but when I checked the barrel stamp it said 5.56 nato. Just stick with 55grain ammo and you'll be fine 5.56 or .223.

[Guest Todd@CIS]

It's my understanding that all Smith ARs are 5.56mm rather than .223.

Your GTG with all 5.56 / .223 ammo...just stay away from Wolf, IMO (I've seen several Smiths, and others, choke on it).

Edited February 15, 2010 by Todd@CIS

[rab]

todd,

the ammo I had ordered was Federal xm193, add said it was real good ammo, does anyone and opinion about that round

[Guest Todd@CIS]

todd,

the ammo I had ordered was Federal xm193, add said it was real good ammo, does anyone and opinion about that round

It's great ammo.

http://le.atk.com/pdf/XM193.pdf

http://le.atk.com/pdf/223VS556.pdf

Edited February 16, 2010 by Todd@CIS

[gotigers]

yes if the barrel is stamped 5.56 it can shoot 5.56. My S&W has 5.56 on the barrel and i shoot both 5.56 and .223 without issue.

I have shot eagle xm193. Good stuff.

Edited February 16, 2010 by gotigers

[Guest ls2tiger]

It's my understanding that all Smith ARs are 5.56mm rather than .223.

Your GTG with all 5.56 / .223 ammo...just stay away from Wolf, IMO (I've seen several Smiths, and others, choke on it).

I shoot Wolf steel...... It's fun to just waste some ammo sometimes. Run the bolt very wet and resist the urge to bumpfire......

[Guest Todd@CIS]

I shoot Wolf steel...... It's fun to just waste some ammo sometimes. Run the bolt very wet and resist the urge to bumpfire......

Consider yourself lucky.

We've yet to have someone come through our 2-day / 1000 round Defensive Carbine class with an AR / Wolf combo and finish without serious malfunction issues.

That's what I'm basing my opinion on.

[Auburn]

todd,

the ammo I had ordered was Federal xm193, add said it was real good ammo, does anyone and opinion about that round

Just curious how much you paid?