.223 vs 5.56

[MarkDido]

I've been putting off buying an AR platform for a while, but now that the election is over, I think it's time.

I know a 5.56 barrel can also safely shoot .223.

I'm not a hunter, so the AR will be strictly for plinking and the Zombie Apocalypse, so tell me why I should go with the 5.56 barrel.

TIA

 

[badkarmamib]

For plinking, you can get mil-surp 5.56 cheaper than commercial .223

 

[azrocks]

Why wouldn't you? Just the fact it increases the chances of finding usable ammo at Wally World would be enough for me to go 5.56.

Plus Zombies respond better to higher velocities.

Who makes .223-only AR barrels anyway?

 

[jmr40]

I've never seen an AR with a 223 marked barrel, most 223 stamped barrels are bolt guns. As far as I'm concerned both are interchangeable anyway, but it bothers some people that some rifles and ammo boxes are stamped 223 and some 5.56. You can shoot either ammo in either barrel. But 5.56 chambers are usually cut a little loose for better reliability and 5.56 ammo CAN be loaded a little hotter. Although it rarely is.

You might run into reliability issues trying to run hotter 5.56 ammo in a 223 chambered semi-auto where the the reverse wouldn't be the case. It'll never be an issue in a bolt gun. There is no advantage to choose a 223 marked chamber.

 

[gojuice101]

I don't think I've ever seen a 223 only barrel. Only ones I've see are 223 Wylde. A 223 Wylde was specifically designed (from what I understand) to shoot both 223 and 5.56.

In theory, there could be a difference in the rounds. In the real world, having tested various types of both ammo, I just haven't seen it. If your choices are 5.56 or 223 Wylde, get whichever. If you're choosing between a 5.56 and an actual 223, just go 5.56. That way you should have no problems shooting whichever type of ammo you want.

 

[Panfisher]

My Remington R15 says .223 Rem on the barrel. No mention of 5.56 anywhere. And unless I was buying and shooting heavier weight bullets I would never be worried.

 

[homatok]

Once the 5.6 cartridge has been fired and resized either 223 or 5.6 can be fired in any 223 rifle. You can always fire 223 in a chamber cut for 5.6 but the other way round, --- not so much. While I agree the two (223 and 5.6) cartridges can USUALLY be safely interchanged, there remains the possibility of a VERY bad experience if we blindly accept the advice that they are always interchangeable. Here are the chamber reamer dimensions for both:



Comparing these dimensions, you can see that under the worst circumstances very bad things could happen. There are, I understand, rifles that are chambered for both, (Mini 14 for one) but unless you have either checked with the manufacturer of your firearm or have made and measured a chamber cast, you should likely fire the first 5.6 ammo using a long string. Be safe, have fun!

 

[Jim Watson]

And it gets worse. The chamber cast article I read showed that you cannot count on the stamp on the barrel. Tolerances are wider than you might think and adherence even to those specs is kind of spotty.

I don't care, I am not going to burn barrel life out of my .223s with surplus.

 

[jim in Anchorage]

If all the .223 vs 5.56 threads on THR. Where printed and made into a book, it would easily go 1000 pages.

 

[d2wing]

I don't think it matters as normal tolerances are generous enough that a 5.56 will be fine in a .223 chamber. The exception would be a very tight target custom barrel in .223 which would normally be a bolt action. All my barrels are 5.56 and I have not seen an AR that is .223 only. I would guess that manufacturers intentional make chambers to accommodate both as to avoid any liability issues. But that is just an opinion. I would chamber a 5.56 round. If it easily fully chambers and the bolt closes over it easily and it extracts easily you should be good. If it dos not chamber fully or is tight in any way you may have an issue. I would try several rounds.

 

[lpsharp88]

.223 vs 5.56 is like the to shoot or not to shoot bare lead in a stock Glock barrel debate. Personally, I'd go with 5.56 just to make absolutely sure I can shoot both .223 and 5.56 in it. Just like I use drop in barrels in my Glocks when I shoot reloads. I like peace of mind knowing my gun isn't gonna blow up in my face. Could I be ok the other way around? Quite possibly, but I'm not gonna chance it

 

[Casefull]

These threads about something that is a non issue are tedious at best.

 

[hps1]

These threads about something that is a non issue are tedious at best.

 

[hps1]

Once the 5.6 cartridge has been fired and resized either 223 or 5.6 can be fired in any 223 rifle. You can always fire 223 in a chamber cut for 5.6 but the other way round, --- not so much. While I agree the two (223 and 5.6) cartridges can USUALLY be safely interchanged, there remains the possibility of a VERY bad experience if we blindly accept the advice that they are always interchangeable. Here are the chamber reamer dimensions for both:

View attachment 225464

Comparing these dimensions, you can see that under the worst circumstances very bad things could happen. There are, I understand, rifles that are chambered for both, (Mini 14 for one) but unless you have either checked with the manufacturer of your firearm or have made and measured a chamber cast, you should likely fire the first 5.6 ammo using a long string. Be safe, have fun!

Have shot handloads almost exclusively in my rifles for the past 60 years but picked up a some surplus M193 5.56 ammo for plinking and experiences some blown primers. I dissected a number of loaded rounds which led me to believe that a combination of the fact that the LC brass was soft (especially that brass that did not have crimped primers and was not stamped with the nato logo), plus a wide tolerance in both powder charges and OAL resulted in blown primers. As homatok stated above, "under the worst circumstances" bad things can happen.

http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=2258010

Most agree that 5.56 ammo is generally loaded a bit hotter than factory .223 and comparing the chart above, reveals that the "freebore" in Nato chambers is twice that of the various commercial chambers. The extra freebore results in a slight reduction in pressures enabling the use of slightly hotter ammo, thus seating the bullets a few thousandths deeper resolved the issue in my rifle.

Regards,
hps

 

[Coal Dragger]

As noted free bore in a 5.56x45mm NATO chamber is longer than .223 Remington. Otherwise the dimensions will be identical aside from extra tight match chambers. The 5.56 has longer free bore to accommodate a wider variety of bullet shapes because the military likes that flexibility. The longer free bore resulted in pressure being lower and velocity suffering, so the solution was to hot rod the 5.56 with more powder than .223 to make it back up. This can make firing full power NATO spec 5.56 in a tighter throated .223 potentially problematic. You're probably not going to blow up a rifle, but you may pop primers out and if it is a semi-auto that popped primer may cause a malfunction by lodging itself somewhere undesired.

Because of this alone I only run AR's with a true 5.56mm NATO chamber. They reliably run most all ammo just fine, with the exception of some low grade plinking fodder that is loaded too light, at least if the rifle or carbine is properly gas ported to run full power 5.56 NATO. That is fine with me since spending $1K on a firearm and expecting to run filthy low grade garbage through it is not on my agenda.

An additional benefit is that typically a true 5.56 NATO chamber will usually not be a tight match chamber, but will not be sloppy either. You will also find that the barrels that go along with a NATO spec chamber are going to be made of CMV 4150, and will be chrome lined or salt bath nitrided all of which enhance reliability, ease of maintenance, and durability. You can expect a good NATO chambered barrel to give sun MOA accuracy with good ammo, running a tighter match chamber might buy you a fractional improvement, but unless you're competing the juice is probably not worth the squeeze in giving up reliability under adverse operating conditions.

 

[MistWolf]

The longer free bore I'd there to allow 5.56 ammo to make more velocity with the same pressures as it effectively increases case capacity.

The free bore does not really do much to accommodate various bullets because the over all length of the round is limited by the magazine

 

[243winxb]

See/Google SAAMI for list -
TECHNICAL DATA SHEET
UNSAFE FIREARM-AMMUNITION COMBINATIONS

This may be an example when reloading. Colt rifle is marked 223. https://thefiringline.com/forums/showthread.php?t=581293

See my post #28

This debate will go on and on and on forever.

 

[boom boom]

Luckygunner has a pretty long comparison of firing 5.56 and .223 cartridges in firearms. Go to luckygunner.com and look under research reports for info.

 

[Coal Dragger]

The longer free bore I'd there to allow 5.56 ammo to make more velocity with the same pressures as it effectively increases case capacity.

The free bore does not really do much to accommodate various bullets because the over all length of the round is limited by the magazine

The longer free bore will accommodate bullet ogives shapes of a wider variety that can still be magazine loaded but that would not fit a shorter throat on a .223.

 

[grandpawj]

Homatak, thanks for the comparison specs. I saved it to my p.c. for reference.

 

[homatok]

"Homatak, thanks for the comparison specs. I saved it to my p.c. for reference."

You are welcome.

 

[Jackal]

Very few companies even offer true .223 chambers anymore, so the question should be: "Why would I buy a .223 chambered AR?" Purposefully limiting your ammo choices seems quite silly.

 

[ColoradoShooter77]

My Mini-14 has a Wydle chamber, both calibers are stamped on the barrel.

 

[Shawn Dodson]

The are two problems with firing 5.56 in a standard .223 chamber: 1) blown primers, which will find their way into your fire control group and jam your trigger, and 2) steel cases will get stuck in your chamber.

Some older second/third tier ARs, assembled shortly after the 1994 semi-automatic assault weapons ban expired in 2004, have barrels marked 5.56 but actually have standard .223 Remington chambers. The problems described above occur overwhelmingly with these ARs.

 

[C-grunt]

Also realize that some of the companies that like to cut corners might not have true 5.56 chambers... coughbushmastercough... My old duty Bushmaster would occasionally pop a primer with 5.56 ammo. So would multiple other guys with their duty rifles.

A friend of mine who is a well respected armorer has told me that he has seen many 5.56 marked barrels that will not fit a 5.56 GO gauge.