# Correct .223/5.56 Dies for AR



## Barrier (Mar 9, 2009)

I am planning to start Reloading for my AR. It is a 5.56 model (stamped on the barrel). How do I know which dies are correct. RCBS makes FL dies in .223 and FL .223 dies marked SB (small base)? Which is the correct one. I have been shooting both mil surplus as well as commercial ammo. I have never had a chamber problem with sticking or failure to seat.
thanks 
Barrier


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## The Norseman (Jan 8, 2005)

Morning Reloading Enthusiasts,

The barrel on my AR15 is marked 5.56 NATO. I have been reloading
with Full Length Sizing Dies.

I have had no troubles yet.

I use the same Dies on my .223 Rem Remington Model 7 and have no
troubles.

If the barrel on your AR15 was marked different I would investigate
further. Autos are funny sometimes with resized ammo, in that
case I would use the Small Base Dies.

See Yeaw


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## Aznative (Apr 6, 2009)

The cartridge deminsions for rem 223 and the military 5.56 are identical. The dies are the same. The difference between these two calibers are kinda like comapring apples to oranges. The difference is in the chambers. The 5.56 Chamber in has a longer leade so you can actually put a little more powder in a 5.56 chamber than a 223 chamber. Longer leade is what Weatherby did to hot rod his cartridges. Plus the military calls for higher pressures in their specs but we cannot be sure of that because they also measure pressure at the bolt face instead of right in front of the chamber as saami does. Like I said the difference is like comparing apples to oranges. As a safe rule you can shoot 223 in a 5.56 but not the other way around. You can find this on this page if you look:
http://www.saami.org/Unsafe_Combinations.cfm
With that said as a warning, I've shot 5.56 in 223 many times with no problems.

As far as you dies go, I would try the regular 223 dies first. Most ARs will work fine with them. The small base are designed to size cases under saami max so that the reloads will shoot well in semis. However, the less you work your brass the longer the brass can be reloaded. Start with the standard fl dies and see if they work.


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## Barrier (Mar 9, 2009)

Thanks for the help. I ordered the FL dies as suggested.
Barrier


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## Savage260 (Oct 21, 2007)

> The 5.56 Chamber in has a longer leade so you can actually put a little more powder in a 5.56 chamber than a 223 chamber


Az, I am guessing you mean since there is a bigger jump to the lands in the 5.56 chamber you can seat the bullet out farther in the neck, so there is room for more powder?

I have read that shooting .223 in a 5.56 chamber will be less accurate. Will this change if you just leave the bullet out a bit farther so the jump to the lands isn't quite so large? I am loading for a 5.56 with 1-9 twist. I am not getting the results I want with 50 and 55gr bullets set to just fit in the mag. If I lengthen the OAL and shoot single shot will this help?


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## Aznative (Apr 6, 2009)

laite319 said:


> > The 5.56 Chamber in has a longer leade so you can actually put a little more powder in a 5.56 chamber than a 223 chamber
> 
> 
> Az, I am guessing you mean since there is a bigger jump to the lands in the 5.56 chamber you can seat the bullet out farther in the neck, so there is room for more powder?
> ...


Compared to a 223 chamber, you can add more powder in a cartridge with a 5.56 chamber before exceeding safe pressures and seat the bullet further out. I would be very afraid to state how much powder you could add since every gun is different. However, you are usually limited to 2.260 with an AR Mag unless you load them single shot as you've suggested. You should get some method down to check COAL before you start pushing the bullet out. Like I just said, every gun is different. Sometimes you just cannot get a gun to shoot well. You then only have two choices: Sell it or fix it.

Rock River uses a Wylde Chamber which is a compromise between the nato chamber and the 223 chamber. It is suppose to be both accurate and safe with 5.56 ammo. In fact, every reamer maker and barrel maker has different specs they use. I've seen 5.56 chambered guns shoot very well. It all depends upon the entire package.


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