[SPLrifleman]

I'm new to the ar I'm told I can load and shoot each without a problem but since I don't know what the differences are in the to I'm not just gonna grab some ammo and fire it

[rjd3282]

There are those that say you can't shoot 5.56 from a 223 chamber. Personally I haven't had anyone explain it to me that makes sense. Some say 5.56 is loaded hotter than 223 but if you look you can find 223 ammo that is faster than 5.56 ammo with the same bullet. Only one way to do that and that's add more powder/pressure. Dimensionally it is the same ammo. Then there are some that say 5.56 uses thicker brass but after extensive testing myself, the two cases weigh exactly the same. Both hold the same amount of water. Then there's the people that say the 223 chamber has a shorter throat and it causes the 5.56 ammo to spike pressures. Again demsionally the same so if it doesn't spike with 223 ammo I don't know how it will spike with 5.56. Also many reloaders adjust the OAL to get the bullet closer to the lands to make it more accurate. I guess they shouldn't do that? The only thing I've ever seen different between 5.56 and 223 is they crimp the primers on the nato stuff.

Flame away.

[c3shooter]

We have talked this over several times here. In a nutshell-

They are similar, not the same- just as 7.62 NATO and .308 Winchester.

The 5.56 is loaded a bit hotter, but the real difference is in the chamber. In some cases, it can be unsafe to shoot 5.56 in a rifle marked .223. The .223 has a tighter chamber. You can shoot .223 ammo in a 5.56 rifle, but not 5.56 in a .223 rifle.

Exception- there is a chamber called .223 Wylde that goes either way. And Ruger firearms are made to go either way, even if it says .223.

For those that say "I've been doing this for X number of years, and I ain't never had no problems...." That's nice. I am repeating what the makers of YOUR rifles and YOUR ammo said. Argue with them- but move down to the end firing point away from other folks.

BTW, the 7.62 NATO/ .308 is the opposite of this- do not shoot .308 in a 7.62 NATO gun.

[Donn]

In addition to what C3 said, I understand the other difference is in the barrel. 223 is a 1/7 twist, 5.56 NATO needs 1/9.

[JonM]

Military m16/m4 have 1/7 twist barrels early m16a2 had 1/9 and m16 and m16a1 were 1/12.

Civilian bolt guns in 223 tend to be 1/12 and very rarely are 1/9 or 1/7.

Most milspec ar15 makers produce barrels in 1/7.

Some companies use 1/7 1/8 1/9 twist on both 556and 223. Caliber is not an indicator of twist rate.

The reason that 556 and 308 are different is the chambers have longer leads on the rifling in both cases its to utilize bullets that are over long in ogive. In 308 its to allow usage of 180 grain bullets and in the case of the 556 its use tracer and ap rounds which can be longer than standard 556 bullets.

If you stick a longer bullet into a shorter lead chamber the bullet can hit the lands and grooves of the rifling this causes an overpressure situation and kaboom.

[bluez]

Originally Posted by Donn

In addition to what C3 said, I understand the other difference is in the barrel. 223 is a 1/7 twist, 5.56 NATO needs 1/9.

Sir, this is not correct.

it depnds on the weight of bullet and we've gone over this.

1/7 is the milspec because they wanted to keep the option of shooting very heavy bullets like 75gr and higher .
But cptrary to internet rumor 1/7 it is not even neccessary for the standard 62 gr military round which is equally accurate in a 1/9 barrell.

Personally I feel that 1/9 is perfect for our civilian purposes since it shoots 55gr and 62 gr equally well and can handle up to 69 gr someitmes more just fine.
And in any event 55gr is the most common civlian bullet.

1/7 is considered more prestigous by many since its the milspec..

And of course some folks DO shoot the heavier bullets like 75 gr, 77gr etc those folks should go w/ 1/7.

My AR's are amix of 1/7 and 1/9 BTW but since i limit myself ( for now) to 62gr and 55 gr bullets they are functionally identical to me ( 55gr also works fine in 1/7 barrells even tho theoretically it should lose some accuracy being "over stabilized")

but all this has nothing to do with .223 vs 5.56 and c3 shooter explained that properly IMO.

[robocop10mm]

The 1/7 twist is actually for the tracer round which is even longer than the standard M-855 62 gr bullet

[bamashooter68]

SPL your AR should be NATO chambered. I dont know of any that arent. If thats the case you can shoot both. I have a 1:9 twist AR and Mini-14 and both can shoot and stabilize short 75gr bullets but not the longer ones like the A-Max. It really depends on the length of the bullet.

[JTJ]

Originally Posted by rjd3282

There are those that say you can't shoot 5.56 from a 223 chamber. Personally I haven't had anyone explain it to me that makes sense. Some say 5.56 is loaded hotter than 223 but if you look you can find 223 ammo that is faster than 5.56 ammo with the same bullet. Only one way to do that and that's add more powder/pressure. Dimensionally it is the same ammo. Then there are some that say 5.56 uses thicker brass but after extensive testing myself, the two cases weigh exactly the same. Both hold the same amount of water. Then there's the people that say the 223 chamber has a shorter throat and it causes the 5.56 ammo to spike pressures. Again demsionally the same so if it doesn't spike with 223 ammo I don't know how it will spike with 5.56. Also many reloaders adjust the OAL to get the bullet closer to the lands to make it more accurate. I guess they shouldn't do that? The only thing I've ever seen different between 5.56 and 223 is they crimp the primers on the nato stuff.

Flame away.

If you want to take responsibility for getting someone injured it is up to you.
Saami .223 chamber length = 2.410"
Wylde .223 chamber length = 2.445"
NATO .556 chamber length =2.550"
Those are huge differences. A .223 fired in a .223 chamber will have a higher velocity than one fired in a NATO chamber because of the different pressure peak. A NATO penetrater or tracer round with their longer bullet length could be catastrophic in a .223 chamber.

[rjd3282]

Originally Posted by JTJ

If you want to take responsibility for getting someone injured it is up to you.
Saami .223 chamber length = 2.410"
Wylde .223 chamber length = 2.445"
NATO .556 chamber length =2.550"
Those are huge differences. A .223 fired in a .223 chamber will have a higher velocity than one fired in a NATO chamber because of the different pressure peak. A NATO penetrater or tracer round with their longer bullet length could be catastrophic in a .223 chamber.

Go back and read my post. If you can find anything I said that isn't true let me know. I'm not anybody's mother let them make up their own minds about things. How would I be responsible for what other people do. It's funny, when I go to the reloading manuals there is no distinction between the two. You can't buy 5.56 dies, you can't buy 5.56 bullets it's all labeled 223 Remington, or .224 bullets. If you are going to talk about things like penetrators or tracers then be specific. I never mentioned either.

Chamber lengths aside the actually round itself is the same length for a given bullet weight. I never said there was no difference in chambers I said there is no difference in the ammo.