.223 remington with 5.56mm NATO brass?

[darkvibe]

First of all my AR is chambered in 5.56mm so I'm not worried about shooting this stuff but I am curious of what exactly I have.

I bought half of a case of ammo being sold as .223 remington. It's once loaded ammo from a company in the midwest. I recieved it and noticed the head stamps are all LC 04 with the nato symbol (circle with a "plus" sign in it) so the brass is from 5.56mm ammo.

So can I have .223 remington even though the head stamps are from 5.56mm ammo? If I understand right the throat angles are a bit different. Does the sizing die change that angle when they are reloaded?

Just wondering what exactly I have. I'm trying to figure out what my gun likes and doesn't like.

edit: or is the brass identical and only the chambers are a bit different?

[DefensiveCarry.com]

[Shizzlemah]

LC04 would be USGI nato-spec 5.56 ammo produced at Lake City - IF it was factory loaded.

It is possible to reload 5.56 as .223 but not the other way around. That usually isn't done because now the headstamp is wrong.. As to positively identifying what you have, call the vendor it came from.

[gotammo]

the difference i believe have to do with head space and the case pressures are higher in 5.56. Problems arise when you have a .223 rem and want to use nato ammo not the other way around.

[darkvibe]

It is possible to reload 5.56 as .223 but not the other way around.

Thanks. I bet that's what happened. I'll shoot the vendor an email to be sure.

It shoots pretty good. Much better than the Remington UMC I was using before.