.223 vs 5.56 performance differences?

Merlin593 · Sep 11, 2014

Just wondering what the current thoughts are on the 2 different rounds from a performance and benefits/drawback perspective.
Let's compare a 55 grain round of each and brass cased only. If we allow steel cased into the conversation it could add some other comparisons that I don't want to address in this post.
I have only put .223 through my gun. I think cost/availability has mainly driven that decision. But my barrel is 5.56 so I can shoot either.
Any big drivers to choose one over another?
Thanks in advance.
Jim

vector03 · Sep 11, 2014

I've experienced tighter groups with 556.

3gunnut · Sep 11, 2014

5.56 can run at higher pressure so that usually equates to higher velocity. Higher velocity usually means less drop at distance which is a plus if you actually shoot at distance.

Downside, in theory, is that higher velocity rounds might wear out your barrel faster, maybe? A lot depends on the barrel.

There are very slight chamber differences between 223 and 556 guns.

I like 223 Wylde chambers which are actually made to shoot both 223 and 556 rounds - I use it in 3gun ... I typically use 223 for close targets and 556 for distance.

Z_Man · Sep 11, 2014

xm193 and .223 55g fmj are very similar as you stated. 5.56 brass and .223 brass are not exactly the same. 5.56 brass is slightly thicker and is crimped. unless you are running a very precise weapon, you won't notice the difference in accuracy. The 5.56 round is slighty more round in shape than .223, thus the dimensional difference in the chamber. so in a 5.56 chamber a .223 will will not be flush the whole length of the throat.

if you are going to reload shooting .223 will make your life a little easier as the brass isn't crimped.

Keep shooting whatever is cheaper/easier to find

dev · Sep 11, 2014

I found XM193 (5.56) to give my rifle better accuracy then 223.
The best way to know is to sample a variety of ammo that you may consider to purchase in bulk and compare. When you reach that conclusion then just purchase the one your rifle likes and functions well. Every rifle is different, every shooter is different. If you reload then test different loads and different case overall lengths until you hit the sweet spot. Keep those numbers forever.

Pinecone · Sep 11, 2014

It depends.

Blackhills 77 grain OTM rounds are 2750 fps in both .223 and 5.56 versions. So no difference.

Furious George · Sep 11, 2014

The difference is in the rifle chamber dimensions and maximum pressure specification. The dimensional differences in the loaded cartridge are negligible.

In a rifle with a 5.56 chamber, you are not going to see any difference worth noting or paying for.

A rifle with a true 223 Remington chamber (actual dimensions, not rollmarking on the bbl) may give better accuracy because of the shorter and narrower throat section.

This same short 223 Remington leade may also give you pressure problems firing the 5.56 ammo loaded to higher pressure. Seen it happen.

I use 55gr M193 5.56 ammo for blasting because it is usually cheaper in larger quantities.

I then reload the brass with high quality bullets using 223 Remington data ('cause that's whats in the manual) for any shooting that requires precision.

Difference between 5.56X45 and 223 Remington explained: click HERE

ObsceneJesster · Sep 14, 2014

I've found 5.56 to be more accurate when compared to cheap .223 but if you're using Match Grade .223 such as Hornady, the Xm193 and M855 usually won't be as accurate.

Vile Shadow · Sep 14, 2014

Z_Man said:
xm193 and .223 55g fmj are very similar as you stated. 5.56 brass and .223 brass are not exactly the same. 5.56 brass is slightly thicker and is crimped. unless you are running a very precise weapon, you won't notice the difference in accuracy. The 5.56 round is slighty more round in shape than .223, thus the dimensional difference in the chamber. so in a 5.56 chamber a .223 will will not be flush the whole length of the throat.

I've found that 5.56 tends to be just a hair longer as well.

Yellowhand · Sep 14, 2014

I honestly can't tell the difference between the two in my mini 14...maybe I just don't care enough to be that discerning though they both hit where I aim it.

amoebicmagician · Sep 14, 2014

I have generally found that .223 out of guns chambered specifically for .223 shoot better and more consistent groups than the same shooting 5.56

.223 wylde chambers in my ARs tend to shoot 5.56 better

My old 1-in-9 twist bushmaster from the old days when they built their reputation shoots both interchangeably

.223 vs 5.56 performance differences?

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