5.56 v 223 REM

rangermonroe · April 18, 2006, 10:21 PM

I am sure that this has been addressed before, but what is the difference?

**Unclenick** · April 18, 2006, 11:28 PM

Metric and English unit naming conventions are the difference. Main thing to watch out for is that there are a bunch of .223" named cartridge variants and a bunch of 5.56 mm named variants. It is easy to mismatch them. .223 Remington and 5.56x45 mm are the two with the same case dimensions and shoot the same diameter bullet (actully .224" or 5.69 mm, despite the cartridge names) and fit in the AR. Generally, those labeled .223 Remington are for commercial rifles. SAMMI says some military rounds are intended for chambers with longer throats than commercial chambers and can cause overpressure in some commercial rifles. You should be alright firing them in an AR variant that doesn't have a match chamber. I've never seen 55 grain ball ammo that wasn't compatible with both, but that's not to say it doesn't exist somewhere. You want to chamber a sample surplus round and check there are no rifling marks on the bullet when you extract it again (unfired). Stay away from firing AP, incendiary, tracer, or other special purpose military rounds in a commercial non-military style rifle if you are unsure. Military match loads with 69 grain boattails should be alright.

Nick

rangermonroe · April 18, 2006, 11:40 PM

Thank you.

For all practical purposes, 223 & 5.56 are identical?

Lycanthrope · April 19, 2006, 01:26 AM

They are teh same dimensions, but vary in terms of pressure. To shoot 5.56 ammo safely you need a 5.56 chamber. With a tight .223 chamber, 5.56 might overpressure.

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April 18, 2006, 10:21 PM	#1
rangermonroe Senior Member Join Date: January 27, 2005 Location: savannah Posts: 758	5.56 v 223 REM I am sure that this has been addressed before, but what is the difference?

April 18, 2006, 11:28 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Metric and English unit naming conventions are the difference. Main thing to watch out for is that there are a bunch of .223" named cartridge variants and a bunch of 5.56 mm named variants. It is easy to mismatch them. .223 Remington and 5.56x45 mm are the two with the same case dimensions and shoot the same diameter bullet (actully .224" or 5.69 mm, despite the cartridge names) and fit in the AR. Generally, those labeled .223 Remington are for commercial rifles. SAMMI says some military rounds are intended for chambers with longer throats than commercial chambers and can cause overpressure in some commercial rifles. You should be alright firing them in an AR variant that doesn't have a match chamber. I've never seen 55 grain ball ammo that wasn't compatible with both, but that's not to say it doesn't exist somewhere. You want to chamber a sample surplus round and check there are no rifling marks on the bullet when you extract it again (unfired). Stay away from firing AP, incendiary, tracer, or other special purpose military rounds in a commercial non-military style rifle if you are unsure. Military match loads with 69 grain boattails should be alright. Nick __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

April 18, 2006, 11:40 PM	#3
rangermonroe Senior Member Join Date: January 27, 2005 Location: savannah Posts: 758	Thank you. For all practical purposes, 223 & 5.56 are identical?

April 19, 2006, 01:26 AM	#4
Lycanthrope Senior Member Join Date: October 1, 2001 Location: PA Posts: 1,752	They are teh same dimensions, but vary in terms of pressure. To shoot 5.56 ammo safely you need a 5.56 chamber. With a tight .223 chamber, 5.56 might overpressure. All you ever wanted to know and more..... http://www.ammo-oracle.com/body.htm