5.56 verse 223 question


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taozen79
July 15, 2009, 10:42 AM
I have a ar15 A1 , I believe, colt upper , barrel marked
C MP C

can it shoot 5.56??????

THANKS for any help

Buddy

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taozen79
July 15, 2009, 11:16 AM
HELP

cyclopsshooter
July 15, 2009, 11:24 AM
dont know for sure but my best guess is 223 but even a 223 can shoot some 556 but its nt always reliable

taozen79
July 15, 2009, 11:34 AM
BARREL:
DIAMETER:
0.625" at the Front Sight Base
LENGTH:
20"
TWIST RATE:
1/12
MARKINGS:
C CM C

NGIB
July 15, 2009, 11:35 AM
As it was explained to me by folks I trust:

If chambered for 5.56 - can shoot either 5.56 or .223

If chambered for .223 - can only safely shoot .223 (headspace & pressure differences)

What's stamped on the gun, 5.56 or .223?

freakshow10mm
July 15, 2009, 11:52 AM
Headspace is the same, leade is longer in the 5.56.

Pretty sure Colt chambers all their guns 5.56.

nhm16
July 15, 2009, 12:02 PM
Headspace is the same, leade is longer in the 5.56.

Pretty sure Colt chambers all their guns 5.56.

Yes, even the early ones marked ".223" on the lower receiver.

taozen79
July 15, 2009, 12:02 PM
BARREL:
DIAMETER:
0.625" at the Front Sight Base
LENGTH:
20"
TWIST RATE:
1/12
MARKINGS:
C CM C

this barrel is older than the ones marked 5.56. it is an sp1
By 1969 and before serial number 1,750,XXX Colt's chrome chamber barrels were marked C MP C, and the proof markings and C were moved to the same spot. This marking was used as late as 1970 or 1971 and serial number 4,552,XXX. The C means Coltís, the M means Magnetic particle inspected, the P for Proof fired, and the C near the muzzle for Chrome chamber. (late C MP C pic provided by yfs200):

freakshow10mm
July 15, 2009, 12:10 PM
Yes, even the early ones marked ".223" on the lower receiver.
The barrel marking is the key, not the lower.

taozen79
July 15, 2009, 12:31 PM
BARREL:
DIAMETER:
0.625" at the Front Sight Base
LENGTH:
20"
TWIST RATE:
1/12
MARKINGS:
C CM C
this is the barrel markings....from the colt sp1

Byron
July 15, 2009, 02:42 PM
I have a AR bought in 1978.It has had a lot of 5.56 put through it and never failed to function and stays accurate. Byron

Lone_Gunman
July 15, 2009, 02:52 PM
Colt's AR's have 5.56 chambers... you are good to go.

SaxonPig
July 15, 2009, 04:21 PM
#32


223 vs. 5.56 (and .308 vs. 7.62x51).

32. There is essentially no difference between commercial .223 and military 5.56 ammo. The same is true with .308 and 7.62 ammo. The military stuff has slightly thicker brass with a tiny bit more length in the shoulder and I hear this is for strength when feeding through full-auto guns that tend to slam the rounds into the chamber violently. But otherwise, there doesnít appear to be any difference that I have noted after many years of shooting both military and commercial ammo through my .223 and .308 rifles, both bolt action and semi-auto although with some guns with tight chambers closing the bolt on military ammo can be a bit snug. It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.

briansmithwins
July 15, 2009, 04:34 PM
32. There is essentially no difference between commercial .223 and military 5.56 ammo. The same is true with .308 and 7.62 ammo. The military stuff has slightly thicker brass with a tiny bit more length in the shoulder and I hear this is for strength when feeding through full-auto guns that tend to slam the rounds into the chamber violently. But otherwise, there doesn’t appear to be any difference that I have noted after many years of shooting both military and commercial ammo through my .223 and .308 rifles, both bolt action and semi-auto although with some guns with tight chambers closing the bolt on military ammo can be a bit snug. It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.

Good explanation. Too bad SAAMI doesn't agree with you. BSW

From: http://www.saami.org/Unsafe_Combinations.cfm

In Firearms Chambered For---Do Not Use These Cartridges
223 Remington--------------5.56mm Military

MT GUNNY
July 15, 2009, 04:42 PM
"Essentially" there is a Difference:
101613

However upon Lots of Discussion And First hand Accounts. You can Safely Shoot .223 in a 5.56 Chamber. But the Opposite, Possible Damage to your Firearm.

John Parker
July 15, 2009, 07:35 PM
Just shoot it and let us know.

nalioth
July 15, 2009, 08:01 PM
5.56 verse 223 question
I have a ar15 A1 , I believe, colt upper , barrel marked
C MP C

can it shoot 5.56??????

THANKS for any help

Buddy
HELP 'bumped"
HELP

If I might point out that it doesn't make sense to expect a fast response when you post during the work day.

Also, "bumping" the thread after a half hour without a response isn't going to send out psychic waves to get everyone to immediately run to their keyboards to answer you.

Please don't do this any more.

Uncle Mike
July 15, 2009, 09:14 PM
Here's an idea... call up Colt and put the question to them.

taliv
July 15, 2009, 09:18 PM
It is a popular misconception that military 5.56 ammo is loaded to higher pressures than commercial .223 but it is not.

it's popular because, iirc, the 5.56nato max avg pressure number is a good bit higher than the .223rem ....buuuuuut... units matter and one is in CUP and the other in PSI, so good luck comparing

tju1973
July 15, 2009, 09:23 PM
.223 is safe in 5.56 chambers, not always the other way around...

Some mfgs are marked .223, but 5.56 is ok--ie Mini 14s...

Always go by the MFG recommendation...

ScrwnyM4
July 15, 2009, 09:26 PM
There is in fact a difference between 5.56 and .223. The pressures for 5.56 are higher. If you are chambered for 5.56 then you can shoot both, it is not recommended to fire 5.56 out of a gun chambered for .223. Click on this site if you want proof. It is from Winchester's own site. http://www.winchester.com/lawenforcement/news/newsview.aspx?storyid=11

SHvar
July 16, 2009, 12:13 AM
There is around 12,000 psi more to a 5.56 over .223. Call colt, ask them, Im sure they will tell you that the chamber is 5.56X45mm.

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