performance differences of .223 and 5.56 in a 5.56 chamber?

[RP88]

I got my AR up. It has a 5.56 chamber, just as I wanted. I've been trying to find out how big of a difference there is (accuracy-wise) between .223 and 5.56 in a 5.56 chamber. So far, the only conclusion I've come to is ".223 is generally less accurate", and that the larger throat does take away velocity from the .223 when put in a 5.56 chamber. Problem there is that there wasn't any details on how much accuracy is lost, and/or if it is noticeable.

So how noticeable is the loss of accuracy? I figure I best learn now so I'm not surprised later.

 

[Birdhunter1]

I can shoot my AR with 5.56 chamber anywhere between .725-1.5" with 3-5 shots using ammunition I reload that is full length sized with a .223 die. So yes some accuracy may be lost and you may not win a bench rest competition but you can still hit varmints all day long with it.

 

[rcmodel]

+1

If you reload 5.56, you do it with a .223 sizing die.

In short, there should be no differance at all, if both the 5.56 and .223 loads are both loaded to the same pressure, with the same quality of bullets.

Commercial .223 is often not as fast as military 5.56 because it is not loaded as hot.

Not because of the 5.56 chamber.

BTW: Some of the most accurate commercial ammo made today for the 5.56 rifle is Black Hills .223 Match ammo and Hornady .223 TAP.

rcmodel

 

[gvnwst]

yeah, the "5.56 chamber" is ment for the hotter loads, with longer bullets. with long bullets in .223 brass, i don't know if there is actually a differance...

 

[Larry E]

My AR has an 8" twist, 5.56 chamber, and with 60 gr Sierra HP's will put 5 in under an inch at 100 yards, and ten 75 gr Hornady HPBT's into 3" at 300 yards with a 12X scope. Both of these are loaded to ~2.24" OAL since I want guaranteed feeding from a mag. OAL's vary from 2.235" to 2.255" at that nominal OAL.