isnt 5.56 the metric conversion of the us measurement .223

chadstrickland · June 13, 2011, 05:16 PM

I mean seriously ..isn't it the same freaking thing...:barf:....( pulls hair out of head ):barf::barf:

Geezerbiker · June 13, 2011, 05:30 PM

It sure is...

Tony

mapsjanhere · June 13, 2011, 05:34 PM

actually 5.56 mm is .218 inches ...

jhgreasemonkey · June 13, 2011, 05:51 PM

Yep. If you ever want to figure it out in the future you can use this simple conversion. I like to use this for reasons of curiosity.
This is the conversion formula for ammo

1 inch = 1.00 Caliber = 25.4mm

Caliber x 25.4 = size in mm (Example: .45 caliber x 25.4 = 11.43 so .45 caliber = 11.43mm)

Metric designation / 25.4mm = size in Caliber (Example: 9mm / 25.4 = 0.35433 so 9mm = approximately .35 cal)

GoOfY-FoOt · June 13, 2011, 05:57 PM

The biggest difference between them is on the inside.
From what I understand, the 5.56 has a smaller powder chamber inside the brass, creating higher pressures. Hence the designation. A 5.56 shot through a .223 designated gun, might cause interesting things to happen.
That's the way it was explained to me.

Niner4Tango · June 13, 2011, 06:29 PM

Same external cartridge dimensions, but,
Difference in case capacity
Difference in chamber dimensions
Difference in maximum pressure

.223 is safe in a 5.56 chamber. But not the other way around

I might be missing your question though

ripnbst · June 13, 2011, 06:33 PM

"Yep. If you ever want to figure it out in the future you can use this simple conversion. I like to use this for reasons of curiosity.
This is the conversion formula for ammo

1 inch = 1.00 Caliber = 25.4mm

Caliber x 25.4 = size in mm (Example: .45 caliber x 25.4 = 11.43 so .45 caliber = 11.43mm)

Metric designation / 25.4mm = size in Caliber (Example: 9mm / 25.4 = 0.35433 so 9mm = approximately .35 cal) "

Or you could know there are 25.4 mm in an inch and understand elementary mathematics to simplify everything.

jhgreasemonkey · June 13, 2011, 07:56 PM

Quote:

Or you could know there are 25.4 mm in an inch and understand elementary mathematics to simplify everything.

Some people including me have a hard time with mathmatics so I keep the formula handy in case I forget and need it. I posted it because I thought it might be useful to the OP next time he is wondering about bullet diameter. Maby I'm taking it the wrong way but this statement sure seems condescending.

Technosavant · June 13, 2011, 08:05 PM

Niner4Tango is correct. They're MOSTLY identical. MOSTLY.

The most major differences are in the chamber throat (.223 is a little tighter with a shorter lead before the bullet touches the rifling) and in the the pressure (5.56 is higher pressure).

.223 is usually used for precision applications like varmint rifles. 5.56 is generally used for combat/defensive rifles. There are some hybrid chambers (like the Wylde chamber) that split the difference a bit to provide a touch more theoretical accuracy than you'd get with the 5.56 chamber but retain the ability to shoot the military surplus 5.56 ammo.

As said, don't shoot 5.56 in a .223 chamber, but .223 in a 5.56 is fine.

Loader9 · June 13, 2011, 08:45 PM

If you have access to the older American Rifleman mags, they did a series on the history of the 5.56. It started life in the early 50's as the 22 Gustafson. That case was built on the 22 Rem Mag. The history is pretty interesting for those that like reading about firearms. Here's a blurp from the article
http://hi.baidu.com/spl900114/blog/i...272f05de9.html

chadstrickland · June 13, 2011, 09:28 PM

Thanks guys for all the help...and I know that this may be a fluke but unknown to me at the time I have been shooting 5.56 in my .223 remy 78 bolt gun for 15 years with no problem...and that's a couple thousands rounds...I know it ain't alot but I never had it mess up..not saying it wont..just a luky fluke

B.L.E. · June 13, 2011, 10:02 PM

25.4 mm is exactly, not approximately one inch. The Bureau of Standards defines the inch as 25.4 mm today.

To convert caliber into gauge, divide 1.67 by the caliber and then cube the answer.

(1.67/.223)^3=420

There! It's a 420 gauge rifle.

Scorch · June 14, 2011, 12:33 AM

Quote:

1 inch = 1.00 Caliber = 25.4mm

Not to be pedantic, but a "caliber" is a unit of measure used to measure holes. 1 caliber = 1/100th of an inch, therefore 1" = 100 caliber. A 30-caliber rifle is not the same thing as a .30-caliber barrel.

B.L.E. · June 14, 2011, 06:08 AM

Caliber comes from the Arabian word for (bullet) mold.

SwampYankee · June 14, 2011, 06:36 AM

Quote:

As said, don't shoot 5.56 in a .223 chamber, but .223 in a 5.56 is fine.

That's not always true. The Mini-14 has a .223 chamber (with a lot of slop) and is perfectly safe to shoot both rounds.

Sport45 · June 14, 2011, 06:39 AM

And how would a person of high caliber respond to a thread like this?

Do we need to get into the differences in bullet diameter and caliber for many cartridges? I wonder if the title was really intended to ask if 5.56x45mm was just the European designation for the .223 Remington. It was properly explained that they were close, but not the same.

madcratebuilder · June 14, 2011, 08:04 AM

Quote:

Originally Posted by chadstrickland

Thanks guys for all the help...and I know that this may be a fluke but unknown to me at the time I have been shooting 5.56 in my .223 remy 78 bolt gun for 15 years with no problem...and that's a couple thousands rounds...I know it ain't alot but I never had it mess up..not saying it wont..just a luky fluke

It's more likely to be a problem with heavier weight bullets as they tend to be longer. Anytime you jam the bullet in to the leade of the barrel you have the possibility of a over pressure no matter what caliber.

Niner4Tango · June 14, 2011, 01:57 PM

The Ruger Mini 14 owners manual says it's ok to use 5.56 ammo. The Target model is for .223 only

Apparently, they tightened up the chamber to improve accuracy.

Tim R · June 14, 2011, 07:51 PM

I know 556 is not safe in a TC contender. Spiderwebs the brass which is a sign of extreme pressure.

June 13, 2011, 05:16 PM	#1
chadstrickland Senior Member Join Date: January 26, 2011 Location: alabama Posts: 537	isnt 5.56 the metric conversion of the us measurement .223 I mean seriously ..isn't it the same freaking thing...:barf:....( pulls hair out of head ):barf::barf: __________________ Two weapons that was designed by the same man still in use by the us military 100 years later...1911 and m2...is there anything that comes close.....lol annd maybe perhaps a sig sauer p226 tac ops edition..

June 13, 2011, 05:34 PM	#3
mapsjanhere Senior Member Join Date: August 6, 2009 Location: Albuquerque Posts: 2,832	actually 5.56 mm is .218 inches ... __________________ I used to love being able to hit hard at 1000 yards. As I get older I find hitting a mini ram at 200 yards with the 22 oddly more satisfying.

June 13, 2011, 05:57 PM	#5
GoOfY-FoOt Senior Member Join Date: January 1, 2011 Location: West Central Florida Posts: 463	The biggest difference between them is on the inside. From what I understand, the 5.56 has a smaller powder chamber inside the brass, creating higher pressures. Hence the designation. A 5.56 shot through a .223 designated gun, might cause interesting things to happen. That's the way it was explained to me. __________________ BILL @ Strongside Arms, Inc. - 1479 W. C-48 Bushnell, FL 33513 352-568-0017 -------------------------------------------------- “Why worry when you can pray? He [God] is the Whole, you are a part. Coordinate your abilities with the Whole.” ~Edgar Cayce~

June 13, 2011, 09:28 PM	#11
chadstrickland Senior Member Join Date: January 26, 2011 Location: alabama Posts: 537	Thanks guys for all the help...and I know that this may be a fluke but unknown to me at the time I have been shooting 5.56 in my .223 remy 78 bolt gun for 15 years with no problem...and that's a couple thousands rounds...I know it ain't alot but I never had it mess up..not saying it wont..just a luky fluke __________________ Two weapons that was designed by the same man still in use by the us military 100 years later...1911 and m2...is there anything that comes close.....lol annd maybe perhaps a sig sauer p226 tac ops edition..

June 14, 2011, 06:39 AM	#16
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	And how would a person of high caliber respond to a thread like this? Do we need to get into the differences in bullet diameter and caliber for many cartridges? I wonder if the title was really intended to ask if 5.56x45mm was just the European designation for the .223 Remington. It was properly explained that they were close, but not the same. __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

June 13, 2011, 05:30 PM	#2
Geezerbiker Senior Member Join Date: March 20, 2011 Location: Willamina, OR Posts: 1,908	It sure is... Tony

June 13, 2011, 05:51 PM	#4
jhgreasemonkey Senior Member Join Date: February 7, 2006 Location: Pacific Northwest Posts: 2,238	Yep. If you ever want to figure it out in the future you can use this simple conversion. I like to use this for reasons of curiosity. This is the conversion formula for ammo 1 inch = 1.00 Caliber = 25.4mm Caliber x 25.4 = size in mm (Example: .45 caliber x 25.4 = 11.43 so .45 caliber = 11.43mm) Metric designation / 25.4mm = size in Caliber (Example: 9mm / 25.4 = 0.35433 so 9mm = approximately .35 cal)

June 13, 2011, 06:29 PM	#6
Niner4Tango Senior Member Join Date: May 28, 2007 Location: Vancouver, WA Posts: 287	Same external cartridge dimensions, but, Difference in case capacity Difference in chamber dimensions Difference in maximum pressure .223 is safe in a 5.56 chamber. But not the other way around I might be missing your question though

June 13, 2011, 06:33 PM	#7
ripnbst Senior Member Join Date: November 24, 2010 Location: Spring, TX Posts: 1,552	"Yep. If you ever want to figure it out in the future you can use this simple conversion. I like to use this for reasons of curiosity. This is the conversion formula for ammo 1 inch = 1.00 Caliber = 25.4mm Caliber x 25.4 = size in mm (Example: .45 caliber x 25.4 = 11.43 so .45 caliber = 11.43mm) Metric designation / 25.4mm = size in Caliber (Example: 9mm / 25.4 = 0.35433 so 9mm = approximately .35 cal) " Or you could know there are 25.4 mm in an inch and understand elementary mathematics to simplify everything.

June 13, 2011, 08:05 PM	#9
Technosavant Senior Member Join Date: May 29, 2007 Location: St. Louis, MO area Posts: 4,040	Niner4Tango is correct. They're MOSTLY identical. MOSTLY. The most major differences are in the chamber throat (.223 is a little tighter with a shorter lead before the bullet touches the rifling) and in the the pressure (5.56 is higher pressure). .223 is usually used for precision applications like varmint rifles. 5.56 is generally used for combat/defensive rifles. There are some hybrid chambers (like the Wylde chamber) that split the difference a bit to provide a touch more theoretical accuracy than you'd get with the 5.56 chamber but retain the ability to shoot the military surplus 5.56 ammo. As said, don't shoot 5.56 in a .223 chamber, but .223 in a 5.56 is fine.

June 13, 2011, 08:45 PM	#10
Loader9 Senior Member Join Date: July 29, 2008 Posts: 949	If you have access to the older American Rifleman mags, they did a series on the history of the 5.56. It started life in the early 50's as the 22 Gustafson. That case was built on the 22 Rem Mag. The history is pretty interesting for those that like reading about firearms. Here's a blurp from the article http://hi.baidu.com/spl900114/blog/i...272f05de9.html

June 13, 2011, 10:02 PM	#12
B.L.E. Senior Member Join Date: December 20, 2008 Location: Somewhere on the Southern shore of Lake Travis, TX Posts: 2,603	25.4 mm is exactly, not approximately one inch. The Bureau of Standards defines the inch as 25.4 mm today. To convert caliber into gauge, divide 1.67 by the caliber and then cube the answer. (1.67/.223)^3=420 There! It's a 420 gauge rifle.

June 14, 2011, 06:08 AM	#14
B.L.E. Senior Member Join Date: December 20, 2008 Location: Somewhere on the Southern shore of Lake Travis, TX Posts: 2,603	Caliber comes from the Arabian word for (bullet) mold.

June 14, 2011, 01:57 PM	#18
Niner4Tango Senior Member Join Date: May 28, 2007 Location: Vancouver, WA Posts: 287	The Ruger Mini 14 owners manual says it's ok to use 5.56 ammo. The Target model is for .223 only Apparently, they tightened up the chamber to improve accuracy.

June 14, 2011, 07:51 PM	#19
Tim R Senior Member Join Date: November 30, 2004 Location: God's side of Washington State Posts: 1,601	I know 556 is not safe in a TC contender. Spiderwebs the brass which is a sign of extreme pressure. __________________ God Bless our Troops especially our Snipers.