5.56mm is not 223?

[SSN Vet]

whats the difference?

the chamber geometry and the rated pressure.

5.56 chambers are cut looser (think full auto) and are rated for higher pressue.

The cartridge exterior geometry is identical. But military ammo is loaded to higher pressures.

from what I've read, many barrels with the .223 Rem stamp can handle the pressure....but how do you know for sure?

There is also a cross over chamber called the Wylde chamber that can handle either.

If your not shooting mil. surp. ammo. I don't think it's an issue.

You can certainly load Lake City brass with data from your loading manual and shoot it in a barrel stamped .223 Rem. However, you must work up your loads seperately from your .223 brass, as the case volume of the LC brass is slightly smaller.

Seems that these days, most ARs have either 5.56 or Wylde chambers.

.223 Rem is predominate on bolt action rifles, where nice tight chambers are desireable for accuracy reasons.

 

[cracked butt]

You can use 556 brass to reload for 223- the only difference is that the 556 brass is going to be thicker in the case head and powder charges aren't going to be interchangeble with 223 brass. If you want to get the maximum performance, I would reccommend winchester 223 brass myself- you can stuff a bit more powder in it than LC brass and get a bit more velocity at the same pressure.

556 ammo is loaded hotter than 223 ammo. The chamber dimensions for 556 are longer and with a longer throat in order to keep pressures within specifications.

An analog to this would be weatherby rifles and cartridges and amateur gunsmiths who tried to make rifles that fired weatherby cartridges on the cheap. Weatherby magnum chamberings have very long throats to increase velocity while decreasing pressure. People tried making rifles chambered in weatherby cartridges out of other rifles and didn't know or understand enough that a standard length throat would lead to the rifle being lockedup solid after the first shot or grenaded after a few.

 

[CZguy]

I've put a fair amount of 5.56 through my Saiga .223. No problems so far.

Be sure to let us know if you have a catastrophic failure.

This is a VERY common question both here and at other forums, and should be made into a sticky.

There seems to be two camps with few fence sitters. Group one says you should fire .223 rounds in a rifle so marked, in order to avoid dangerous over pressure. Group two claims to have shot thousands of rounds thru there favorite bolt action .223, with no ill effects.

Personally I follow SAAMI specifications.

 

[rondog]

Um, I think this is related and not OT, but is there any difference like this between commercial .30-06 and milsurp .30-06?

 

[ggarfield965]

Wikipedia did a good job of explaining it, as it does for a lot of stuff.

 

[WardenWolf]

And group three says that some rifles that say .223 are, in fact, designed to handle 5.56 and that you should ask the manufacturer if you're unsure.

 

[esq_stu]

There are many many listings on Gunbroker.com that are for AR15s and uppers and they say .223 in the listing. I suspect they are really 5.56 because they are milspec in every other particular. I don't read those listings any further and I probably have passed over some good deals. But if I have to ask every darned seller the caliber of his gun, I will go nuts. I will just have to wait a listing to come along that doesn't just blow off such a critical detail.

 

[saigafreake]

I kind of find hard to believe the izmash plant would buy tooling for making 223 chambered saigas when the already have the 5.56 tooling for aks.

 

[ggarfield965]

5.56 mm for AKs? Do you mean 5.45 mm Soviet? Why would an AK rifle be chambered for the AR-15 cartridge?

 

[ilike223s]

OH i like the LC brass for my t/c and my tikka,,good tuff stuff the LC brass,,
MY mini 14 can shoot both,223 and 5.6 The hand book that came with it,says its ok to shoot both,, But the 5.6 is a hotter round,for sure,I shot both out of my Tikka,and can tell the dif, in felt recoil.from factory in both 223 and 5.6,

 

[ilike223s]

6.8 spc. Im liking what I see

I been looking at the 6.8 SPC. and Im liking what I see for a Medium power gun for Deer,I think that would really fill in nice for 100 yard Deer round,in a bolt gun,
Does any one have a bolt gun, for this..whats your thoughts .

 

[X-Rap]

I think I'm pushing 25 gr. of 335 and no problems with LC or civi brass.

 

[madcratebuilder]

Somebody forgot to tell my guns I have AR uppers in DPMS, FN, and Colt as well as a few bolts and they all shoot the same ammo seamlessly.
LC in all the .223 + .223 in all the 556. On top of that I reload them all the same and nobody got hurt.
Is it the same for 7.62 and 308? Heaven help me if it is.

Shooting 5.56 in a .223 chamber is not a safe practice. The leade in a .223 chamber is shorter, firing a 5.56 in it may cause on over pressure.
7.62 vs. 308. Depends on the head space. Some rifles can safely fire both, some can not.
If you have a severe over pressure you may have part of the receiver/bolt impact your cheek bone, you'll get the message.

 

[Highland Ranger]

I have a case of winchester rounds that says "7.62x51 (308 win)" the sammi page also does not address the difference . . . . so is there one?