5.56 vs .223

[doonan75]

Yes I know that they are slightly different but my problem is that my Colt Hbar has 5.56 on the barrel and 223 on the reciever. It has a 1:9 twist rate. Which round should I use?

[LCPL 4]

5.56 and .223 can be fired in a 5.56 chambered/barreled rifle. 5.56 in a .223 chamber is not recommended because it may lead to higher pressure.

For a 1:9 twist I usually stay around 50 to 69 grn ammo. Some 20"'s have been known to fire 75 grn boat tails or 75 grn a-max (edit) accuratly but it depends on the individual rifle and what it likes.

[okie shooter]

You anwsered the question, as the barrel which has the chamber says 5.56 thus the chamber is cut for 5.56x45, not .223 rem. As stated above the rifle should function with either. I understand as above, the .223 chamber has problems with 5.56 but not the other way around.

[cfish]

Sometime last year the American Rifleman magazine did a three page article on this very subject,. It was very informative and had great info in it for those who ask this question. I learned things I didn't know.

[Jagman]

I have an hbar target model colt in .223, cannot fire 5.56 through it at all, the
tolerances are so tight that the 5.56 will not function in it. Absoluetly zero problems with .223 marked ammo.

[Lon Moer]

Ammo Oracle (ammo.ar15.com)

[45B@cav]

Always trust the barrel markings. You can't go wrong like that.