Author Topic: Does .223 Equal 5.56? (Read 8682 times)

whitfang · « **on:** January 21, 2009, 03:15:11 PM »

I've found a good deal on an Encore .223 heavy barrel (for coyotes), but I've never owned that caliber.

Does .223 equal 5.56? Can the cartridges be interchanged safely?

Or is this the same thing as interchanging civilian .308 and military 7.62x39? I've read that strength of powders in those cartridges can vary, the hardness of the primers can be a problem, case dimensions are different...etc.

torpedoman · « **Reply #1 on:** January 21, 2009, 04:07:16 PM »

if memory serves you can fire 223 in 5.56 chamber but not the reverse there is a 223wilde chamber that fires both with better accuracy. This info is for semiauto rifles i dont think the encore would notice the difference.

trotterlg · « **Reply #2 on:** January 21, 2009, 06:00:39 PM »

Thay are basically so close as to be interchanble. There are pressure differences, but the chambering is the same. I don't think you have any thing to worry about at all. Larry

whitfang · « **Reply #3 on:** January 22, 2009, 01:29:18 AM »

Hey, Great!!! That will save me a bunch of money on ammo!!!

Thanks for the information.

cjclemens · « **Reply #4 on:** January 22, 2009, 12:51:18 PM »

The dimensions are the same size, but with the higher pressure, you can sometimes get stuck cases; especially in handi rifles. Also, 5.56 will have a mil spec primer in it, which is a bit harder than regular primers. Some rifles do not hit the primer hard enough to fire the round every time, so you'll just have to try a box of it and see what happens.

sk330lc · « **Reply #5 on:** January 22, 2009, 01:03:26 PM »

I had a 24" Encore barrel in 223 Rem. I could not shoot 5.56x45 Mil spec ammo in it . The primers would crater and even pierce because of High pressure. Also had a few cases split. So don't go hog wild buying ammo until You try a few rounds.

whitfang · « **Reply #6 on:** January 22, 2009, 04:10:46 PM »

Good idea - I won't order 1000 rounds or so until I'm sure the ammo shoots ok.

Thanks.

Dave in WV · « **Reply #7 on:** January 25, 2009, 06:00:26 AM »

No they are not interchangeable.
http://www.saami.org/Unsafe_Combinations.cfm

cjclemens · « **Reply #8 on:** January 25, 2009, 11:33:05 AM »

Has anyone read that whole list? It looks like it was written for the idiot that would jam anything in his rifle that will fit in it. Honestly, who sticks a 20 ga. shell in a 12 ga shotgun and expects it to work? And how the heck do you even get a 44 mag in a 45 auto pistol?

Guy Pike · « **Reply #9 on:** January 29, 2009, 09:59:58 AM »

Oddly I can't find any conversion factor that makes .223 or .224 inches equal 5.56 mm! Always comes out 5.66 or 5.68.

45-70.gov · « **Reply #10 on:** January 29, 2009, 10:53:08 AM »

i understand the throat is longer on 5.56 nato

torpedoman · « **Reply #11 on:** January 29, 2009, 01:33:49 PM »

Quote from: 45-70.gov on January 29, 2009, 10:53:08 AM

i understand the throat is longer on 5.56 nato

Thast the whole difference. dont try to hold the gun folks to real math they dont care ,the 9 mil makarov is 10 thous bigger in dia than the 9mm luger. the 815x46 i have is the same bore size as 762 or 308 or 32

Grumulkin · « **Reply #12 on:** January 30, 2009, 02:46:11 AM »

If you check the Hornady manual, you will find that the case dimensions are EXACTLY the same.

Graybeard · « **Reply #13 on:** January 30, 2009, 05:08:00 AM »

The case is the same. Once upon a time you could pretty much depend on military brass being a bit thicker thus heavier than commercial but not so anymore. Some commercial cases are actually thicker and heavier than some military these days. So that's not really a point you can depend on.

Dimensionally the two cases are thus the same. The differences then are in chamber specs and pressure specs. The 5.56 is spec'ed with a heavier bullet at higher pressure and has a longer throated chamber as a result.

So it boils down to can you fire either in the chamber of the other. Yeah they'll fit and yeah in general they will work. You can pretty much depend on the .223 working in a 5.56 chamber but in some ARs the softer primers might be a problem. With few exceptions the 5.56 will function fine in most .223 chambers as well but some few seem not to work well with them.

It's really the same round just loaded differently.

jro45 · « **Reply #14 on:** February 02, 2009, 07:55:50 AM »

The 7.62X39 and the 308 both have the same mouth its .10 but the shells are differant.
As far as the .223 and 5.56 shells go I no that the mouth is the same but do not know if the shells are the same.

Graybeard · « **Reply #15 on:** February 02, 2009, 08:16:57 AM »

I know critters have mouths but didn't know cartridges did?

What are you calling the "mouth"?

alsaqr · « **Reply #16 on:** February 02, 2009, 02:14:30 PM »

In 1968 I came into a large quantity of M193 military ball ammo. Had my .222 Sako re-chambered to .223. That gun has fired over 4,000 rounds of 5.56mm ammo without a bobble. Tens of thousands of rounds of 5.56mm ammo have been fired from my Remington 788, Remington 700, CZ 527 and Ruger #1 with no problems ever.

Strange that SAAMI waited 20-30 years to inform us of this "danger". They did it about the time that lots of milsurp ammo became available. Looks like they were worried about the competition.

ShottieMan · « **Reply #17 on:** February 03, 2009, 01:16:52 PM »

If I were you, I wouldn't try it! Why not err on the safe side rahter than chance it to save a few dollars here and there.

Also.....it's 7.62x51 not 7.62x39 that is equivilant to the .308!

S.S. · « **Reply #18 on:** February 03, 2009, 03:48:27 PM »

No problem firing 5.56x45 in a .223 Rem. chamber.
No problem firing .223 Rem. in a 5.56x45 chamber.
If reloading military brass start with the minimum load
in your load data due to less case capacity in some of
the older thick brass military cases. Especially old
Lake City stuff. The only exception I have to what
I have stated is H&R/NEF Rifles. their chambers seem to be
extremely tight and occationally military 5.56 surplus ammo
cases will stick in the chamber when fired.

saltydog · « **Reply #19 on:** February 14, 2009, 03:13:35 AM »

This topic is well covered on the internet ( please read some of the articles) and in simple as Dave in WV put it NO they are not interchangable and interchanging them "could be dangerous". Rifle chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues. Lots of funky info being thrown about here. First - I think you meant to compare the 308 WIN to the 7.62x51 NATO not the 7.62x39 - look them up and you will find they are not the same either. Second - 223 REM and 5.56 ammo is not the same if built to specs. Sources of accurate info: http://www.fulton-armory.com/556-vs-223-Chambers.htm ; http://en.wikipedia.org/wiki/.223_Remington ; http://www.ar15armory.com/forums/556-223-Ammunition-Chamber-Dimensions-t22582.html . Reloading mil spec brass also has a few twists - most dies are cut for 223 REM and once you resize the cases you will have brass sized to 223 REM specs - however if using mil spec brass you have to consider the possible thickness difference and reduce loads accordingly. Same reloading cautions apply to mil spec brass in 7.62x51 loaded for a 308 WIN rifle.

alsaqr · « **Reply #20 on:** February 14, 2009, 04:03:06 AM »

Guys get on these sites and spout all kinds of mythological crap about the differences between 5.56 mm and .223 chambers. Fact is that there are more than a dozen different chambers for the .223 and 5.56 mm cartridges: Which chamber are you talking about? A gunsmith friend tells me that no current US maker that he is aware of uses a SAAMI dimension chamber for the .223. I have fired somewhere between 250,000 and 500,000 rounds of 5.56mm ammo in .223 chambers since 1968 with no problems at all. It is not a good idea to fire military OR civilian ammo in a tight match chamber.

http://www.ar15barrels.com/data/223-556.pdf

As for US 5.56mm brass being thicker than commercial brass that is all bull crap too. I weigh all my cases and sort them by weight for accuracy. I have military brass cases going back to 1964. They are NOT thicker than commercial brass. BTW: The heaviest .223 brass out there is Federal Gold Metal and Lapua.

http://www.ar15barrels.com/tech.shtml

KAYR1 · « **Reply #21 on:** March 10, 2009, 02:45:32 PM »

This has always been confusing, and had conflicting reports. I want to mention that I personally witnessed a shooter have a case failure in his .223 Handi Rifle while shooting Federal 5.56 NATO factory ammo. The case rim was ripped off, and the case body was stuck in the chamber.

I am not sure of the cause, but this happened before he got through a 20 round box of 5.56.

cjclemens · « **Reply #22 on:** March 10, 2009, 03:01:23 PM »

I've seen a lot of stuck 5.56 cases in a handi rifle, but never a failure like that. Maybe it had something to do with it being Federal.

alsaqr · « **Reply #23 on:** March 10, 2009, 03:08:40 PM »

Had a Handi Rifle in .223. The thing had a huge out of round chamber that left the cases so swollen out of shape that they had to be really forced into the sizing die. In spite of that it did shoot really well.

emsemt911 · « **Reply #24 on:** April 01, 2009, 03:12:21 PM »

You can shoot a .223 rem in a 5.56 barrel.
Yoiu CAN NOT shoot a 5.56 in a .223 rem barrel!

pastorp · « **Reply #25 on:** April 01, 2009, 04:27:09 PM »

You guys kill me.

Old wives tales and folk lore.

You should listen to Bill, he has it right...................I've shot military 7.62x54 interchangeabely with .308 winchester rounds in military and civalian guns for years. Done the same thing with 5.56 and 223. You guys are really funny.

Regards,

Badnews Bob · « **Reply #26 on:** April 01, 2009, 05:11:41 PM »

My Rem 7615 is marked on the barrell 5.56 NATO or .223 rem they are the same thing.

nomosendero · « **Reply #27 on:** April 02, 2009, 01:15:19 AM »

helotaxi · « **Reply #28 on:** April 07, 2009, 12:51:36 PM »

Looks the same must be the same right?

SHOOTALL · « **Reply #29 on:** April 07, 2009, 01:12:40 PM »

hum , looking at what is expected from a round might help . Military brass seems harder when resizing . Could we assume it helps in the gun being used on full auto or to make sure head seperation does not happen in a hot dirty sticky chamber in battle when cleaning might not be wise ? The primer is harder in military ammo to keep the weapon from having a SLAM FIRE . I know this from springfields lititure and because i buy them now for use in a M-1A , they also have them for small rifle . I have seen guns marked one way or the other and dual marked . It would be wise to contact the builder of the gun as he should know how it was set up and for what ammo should be used .