Virginia Gun Owners Forum - VGOF

I know the differences between 5.56x45 and .223 has been discussed at length here, but I just have one more question...

Any problem with loading a magazine with both calibers and cycling through it? I can't imagine so, but wanted to ask. For instance, I have these .223 tracers (will have soon, anyway) and I was thinking about loading up a 30 round magazine with 5.56 and a .223 tracer every 5th round. Anyone see a problem with that? Maybe I should just shoot all .223 since it's much easier to find anyway?

In your 5.56mm AR:

If it feeds it reliably, no problem. Go for it.

Unless I'm mistaken I thought the difference was more in the chamber of the rifle than in the cartridges themselves. Meaning a rifle chambered for 5.56X45 will feed/chamber .223 cartridges but a rifle chambered for .223 Remington may have pressure issues with 5.56X45 ammo as some of it has bullets that are on the heavy side and therefor stick out of the case mouth farther.

I have a couple of .223 varmint rifles (Remington M700 and Savage) that chamber/fire 5.56X45 just fine but some rifles do have problems.

l've read several times that with some AR manufacturers the barrel may be marked 5.56X45 but the chamber is closer to .223 Remington. Many folks have said the only way to know for sure is to have your rifle's headspace measured and to have the leade checked to insure you have sufficient space between the bullet and the start of the lands/rifling.

M1A4ME wrote:Unless I'm mistaken I thought the difference was more in the chamber of the rifle than in the cartridges themselves. Meaning a rifle chambered for 5.56X45 will feed/chamber .223 cartridges but a rifle chambered for .223 Remington may have pressure issues with 5.56X45 ammo as some of it has bullets that are on the heavy side and therefor stick out of the case mouth farther.

I have a couple of .223 varmint rifles (Remington M700 and Savage) that chamber/fire 5.56X45 just fine but some rifles do have problems.

l've read several times that with some AR manufacturers the barrel may be marked 5.56X45 but the chamber is closer to .223 Remington. Many folks have said the only way to know for sure is to have your rifle's headspace measured and to have the leade checked to insure you have sufficient space between the bullet and the start of the lands/rifling.

Brass wise, they are identical. The differences are in the throat and leade. 5.56mm has more play to allow for higher pressures under adverse environmental conditions and the firing of many rounds. Firing 5.56mm in .223 may cause a problem. It may accelerate the wear on the gun, it may shorten the life of the brass, it may go boom. It may do a lot of things, but is generally inadvised. Rick's AR is 5.56mm, which will shoot both. It tends to shoot .223 less accurately than a .223 chamber/throat/leade will, but since there is extra play, you don't have to worry about excess pressure.

.223 chambers should shoot only .223
5.56mm can shoot either, but the 5.56mm ammo has more velocity and recoil.

Externally they are identical but not internally. The basic difference in the cartridges is in the pressure...5.56 is higher pressure. 5.56 brass is thicker thus able to hold less powder. The other difference is not in the cartridge but the chamber and throat (I believe) - .223 and 5.56 uppers are not equal.

So, as Garrett pointed out free bore is different. Hence, accuracy will be affected. Shooting 5.56 from a .223 chamber also runs the risk of achieving unpredictable results due to the pressure differences...

I do trust Garrett's depth of knowledge and technical abilities, but I wouldnt do it unless there was no alternative.....probably cause I'm just stubborn...

The pressures are different, and 5.56mm is hotter. It is hard to tell by how much though as they measure pressure differently.

.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

That is generally assumed to be true, but military brass very considerably. I forgot who took the time to do it, but they measured several common 5.56mm military brass cases and found that some are the same thickness as .223 and other are much thicker. Sometimes even the same "brand" would vary that much between lots.

The pressures are not directly comparable because they measure them differently. However, the following is always good advice:

1. Don't shoot 5.56m in a .223

2. Start low on handloads and work them up for your gun.

BTW - I took my AR out again the other day with the Marines. I had just received my AR15 LULA from FedEx that day. Used it to load up some magazines - probably burned through a couple hundred rounds. I had some M855 Lake City ball ammo and some WWB. Both fired pretty much flawlessly. I did have a couple of stovepipes, but I wasn't paying enough attention to make note of which ammo was in that mag or anything. We were just blasting

Does life get much better than a nice AR15 and a LULA?

My AR (a DPMS MOD A-15)

lists the cal this way

CAL .223-5.56MM

so is one better to shoot than the other


currently the only thing I've run through it is remington .223

jaywade wrote:My AR (a DPMS MOD A-15)

lists the cal this way

CAL .223-5.56MM

so is one better to shoot than the other


currently the only thing I've run through it is remington .223

What are you using it for? .223 tends to be cheaper. I shoot whatever I can get for under $300/1000, which right now is 5.56 Federal XM193 bulk boxes that I got for $269. Palmetto has a deal on AE223 right now, for just punching holes in paper, it's perfectly fine.

gunderwood wrote:

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

That is generally assumed to be true, but military brass very considerably. I forgot who took the time to do it, but they measured several common 5.56mm military brass cases and found that some are the same thickness as .223 and other are much thicker. Sometimes even the same "brand" would vary that much between lots.

The pressures are not directly comparable because they measure them differently. However, the following is always good advice:

1. Don't shoot 5.56m in a .223

2. Start low on handloads and work them up for your gun.

allingeneral wrote:BTW - I took my AR out again the other day with the Marines. I had just received my AR15 LULA from FedEx that day. Used it to load up some magazines - probably burned through a couple hundred rounds. I had some M855 Lake City ball ammo and some WWB. Both fired pretty much flawlessly. I did have a couple of stovepipes, but I wasn't paying enough attention to make note of which ammo was in that mag or anything. We were just blasting

Does life get much better than a nice AR15 and a LULA?

Sounds like you need more oil on the BC or bolt. From what I hear, those that train tactical carbines say the #1 reason for AR jams/stoppages is lack of oil. They add a few drops in the right place and most of them function flawlessly.

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

Hey DK, I don't want you to think that I am breaking your stone's but I must tell you that putting something on here that just say's CUP'S will have some of our brother and sister forum members confused. So please forgive me for the following.

CUP stand for Copper Unit's of Pressure a type of measurment used in the weapons and ammunition industry.
Bill

I have loaded both in my mini 14 and the AR that I use to have with no problems. Then again I haven't seen any .223 ammo or combination of that the mini won't handle. Ar's can be finicky.

SgtBill wrote:

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

Hey DK, I don't want you to think that I am breaking your stone's but I must tell you that putting something on here that just say's CUP'S will have some of our brother and sister forum members confused. So please forgive me for the following.

CUP stand for Copper Unit's of Pressure a type of measurment used in the weapons and ammunition industry.
Bill

No sweat Bill. I guess I should have spelled it out. I thought it would be intuitively obvious to even the most casual passerby of average intelligence...

DK, you must remember that Henry read's these boards. So you must spell everything out with small words and as few as possible. LOL
Bill

SgtBill wrote:

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

Hey DK, I don't want you to think that I am breaking your stone's but I must tell you that putting something on here that just say's CUP'S will have some of our brother and sister forum members confused. So please forgive me for the following.

CUP stand for Copper Unit's of Pressure a type of measurment used in the weapons and ammunition industry.
Bill

I thought CUPs was usually designated with letter sizes?

SgtBill wrote:DK, you must remember that Henry read's these boards. So you must spell everything out with small words and as few as possible. LOL
Bill

Bill - it dont get no simpler than C-U-P...

gunderwood wrote:

SgtBill wrote:

zephyp wrote:.223 is rated somewhere around 50k CUP max and 5.56 around 60k max. And pressures will be different even when using the same powder because the 5.56 is thicker thus having less space inside...

Hey DK, I don't want you to think that I am breaking your stone's but I must tell you that putting something on here that just say's CUP'S will have some of our brother and sister forum members confused. So please forgive me for the following.

CUP stand for Copper Unit's of Pressure a type of measurment used in the weapons and ammunition industry.
Bill

I thought CUPs was usually designated with letter sizes?

Double D's are downright nice!