In article . com,
Ringmaster wrote:

That Winchester warning only applies to heavier bullets because the
ogive is
blunter and the bullet is longer.

That's only the Winchester statement. They are not the only ones who
speak on the topic. Read the SAAMI website. Anybody that tells you
there is no difference between a 223 and a 5.56 doesn't know what they
are talking about.

External case dimensions are interchangeable.

Once again ...... SAAMI states that it is an unsafe
practice to shoot 5.56 in a gun that is only designes to shoot 223.
They are the experts.

Right, fer sure, uh huh, all them reloaders and reloading manuals speak
from pure ignorance, uh huh, ok........

How many rounds you fired thru that new toy of yours yet?

You're missing a couple points. First, IIRC your toy is chambered for
5.56, so firing 223 Rem is perfectly safe. Second, IIRC 5.56 NATO mil
spec ammo is exclusively FMJ to comply with the international
protocols. On that one I could be wrong, but all the specific 5.56 ammo
I've ever seen has been FMJ.

Flogged this one to death. You're clutching at one poor straw to avoid
looking like a complete ignoramus, whereas I'm happy to concede that
SAAMI recommend not firing 5.56 NATO in a 223 Rem chamber. Many do,
have & will, tho, and I doubt you can find a single example of a rifle
blowing up as a consequence. Frankly I don't care enough to x-post this
to rec.guns and ask, but be my guest.......

Meanwhile, go learn how to shoot your new toy and more importantly,
when *not* to shoot it. Everyone will be safer and happier.

PDW