.223 vs 5.56 Is there a difference?

[BangBang]

That cheap ass steel case Tula .223 is the first stuff I run through any new AR I get.

If it'll cycle that weak stuff reliably, it'll run on anything.

@FatAlbert isn't lying about the smell either.

That **** STINKS!

 

[palmettomoon]

Ruger's manuals indicate it is safe to shoot either in their .223 Rem marked rifles.

It might, might result in higher pressure when trying to shoot 5.56mm (>55 grain proj.) NATO in a tight .223 REM chamber. Maybe. The longer SS109 bullet (M855 for you kiddies) may, may engage the rifling of a short leade chambered .223 Rem rifle or pistol and may be set back a smidgen.
Please show me where some asshat has blown himself up with factory ammunition in a good clean rifle shooting either marked cartridge any either marked chamber.