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View Full Version : 5.56 on a .223 marked Colt AR?


GuillermoAntonio
09-14-2012, 11:09 AM
My friend owns a Colt AR-15 marked as chambered in .223, we are shooting it next week and Im taking some XM193 and 855 with me, he claims he has run this ammo trough his rifle before, but Im a bit afraid of using it, whats you guys' take?
Also, I just bought me a savage trophy xp in .223, can I use 5.56 on that?

Thanks!

stix213
09-14-2012, 11:13 AM
5.56 has a higher max spec than .223, so if you shoot a 5.56 that is at the higher end, and the .223 rifle can't take any more pressure than the .223 spec requires, you could get a catastrophic failure.

b.faust
09-14-2012, 11:16 AM
I'd say, to be safe, no, don't shoot 5.56 through a barrel marked .223

People do, and they get away with it, but common convention says that .223 is loaded to lower pressures than 5.56 mm

Smarter folks than I have stated time and time again, that 5.56 (in .223 chambering) will add excessive stresses and wear on the rifle, and potenitally can be dangerious.

Again, I know folks do use 5.56 in .223, and personally I've never seen first hand accounts of falure do to this, but better safe than sorry.

five.five-six
09-14-2012, 11:19 AM
I like 5.56

FeuerFrei
09-14-2012, 11:27 AM
Origional Colt SP01 will handle 556 no problem.
Smoke 'em if you got 'em.

mif_slim
09-14-2012, 11:27 AM
It'll Es-plod on you!!! ;)

1000stars
09-14-2012, 11:33 AM
Origional Colt SP01 will handle 556 no problem.
Smoke 'em if you got 'em.

Isn't the barrel stamped 5.56?

FeuerFrei
09-14-2012, 11:42 AM
Isn't the barrel stamped 5.56?

Receiver says 223, barrel says 556. Go figure. :rolleyes:
Shooting buddy in NV has one and he runs milsurp 193 & 855 in it all the time.

joemoia
09-14-2012, 12:36 PM
SAAMI says:

http://www.thegunzone.com/556v223.html

USAbodypilot
09-14-2012, 1:02 PM
Receiver says 223, barrel says 556. Go figure. :rolleyes:
Shooting buddy in NV has one and he runs milsurp 193 & 855 in it all the time.

I have a Colt with the same issue - upper receiver says .223 and the barrel says 5.56.

No that this is smart to do but I chose to ignore the receiver and have blown a few thousand 5.56 down the pipe and survived. YMMV.

Rorge Retson
09-14-2012, 1:04 PM
I wouldn't. I've grown accustomed to my extremities.

Seriously, get a 5.56 round on the upper end of spec and a .223 barrel on the lower end and....??

FLIGHT762
09-14-2012, 1:51 PM
Origional Colt SP01 will handle 556 no problem.
Smoke 'em if you got 'em.

This is correct ^^^^^^^^^^^^ the older Colt SP-1's were marked on the lower receiver 223 Rem. for the caliber. The barrels were not marked with the
5.56 until later production. Those older Colts have a Colt 5.56 chamber and are safe to shoot 5.56 ammunition as long as the rifle is a Colt factory unaltered rifle. If your buddy's rifle is an older Colt AR-15, it will be fine with the XM-193 5.56 ammo

The SP-1's also had a 1/12" twist barrel. M-193 will work fine in those. M-855 will not stabilize in the old 1/12" barrels. I believe that's when the barrels started to be marked 5.56 and give the twist rate on them when the Military adopted the M-855 round.

As far as you using the 5.56 ammo in your Savage XP bolt gun, the answer is NO. You need to use SAAMI spec 223 Remington ammunition in the XP.

Ubermcoupe
09-14-2012, 1:55 PM
SAAMI says:

http://www.thegunzone.com/556v223.html

This helps.

Look up SAAMI pressures for .223 & 5.56 and you will notice a difference. That difference could be as little as nothing, or at minimal, excessive wear and tear on your buddy’s rifle, or it could be as bad as a catastrophic failure.

Just because you can, doesn’t mean you should.

As a general rule of thumb .223 in 5.56 is okay (although accuracy may suffer), but the not the other way around.

If it were my rifle, I wouldn’t let you shoot 5.56 out of my .223. :o

joemoia
09-14-2012, 2:54 PM
I downloaded a copy of this some time ago for a handy reference

http://www.saami.org/specifications_and_information/publications/download/SAAMI_ITEM_211-Unsafe_Arms_and_Ammunition_Combinations.pdf

MrPlink
09-14-2012, 3:42 PM
You guys understand that if I engrave 50bmg on a 10-22 that doesent exactly make it so?

Dave07997S
09-14-2012, 4:35 PM
My friend owns a Colt AR-15 marked as chambered in .223, we are shooting it next week and Im taking some XM193 and 855 with me, he claims he has run this ammo trough his rifle before, but Im a bit afraid of using it, whats you guys' take?
Also, I just bought me a savage trophy xp in .223, can I use 5.56 on that?

Thanks!

Where does it say .223? On the lower receiver or on the barrel near the flash suppressor? My preban R6500 had .223 on the lower receiver but 5.56 C MP 1/7 on the barrel, thats whats important.

Dave

Dave07997S
09-14-2012, 4:36 PM
I have a Colt with the same issue - upper receiver says .223 and the barrel says 5.56.

No that this is smart to do but I chose to ignore the receiver and have blown a few thousand 5.56 down the pipe and survived. YMMV.

I think you mean the lower receiver...mine was on the lower receiver.

Dave

GuillermoAntonio
09-14-2012, 5:13 PM
5.56 has a higher max spec than .223, so if you shoot a 5.56 that is at the higher end, and the .223 rifle can't take any more pressure than the .223 spec requires, you could get a catastrophic failure.

Where can I verify those numbers?



Isn't the barrel stamped 5.56?

Thats what we need to check.

Receiver says 223, barrel says 556. Go figure. :rolleyes:
Shooting buddy in NV has one and he runs milsurp 193 & 855 in it all the time.
This is goo info, thanks

SAAMI says:

http://www.thegunzone.com/556v223.html

Great read!

I have a Colt with the same issue - upper receiver says .223 and the barrel says 5.56.

No that this is smart to do but I chose to ignore the receiver and have blown a few thousand 5.56 down the pipe and survived. YMMV.

What kind of 5.56 ?


This is correct ^^^^^^^^^^^^ the older Colt SP-1's were marked on the lower receiver 223 Rem. for the caliber. The barrels were not marked with the
5.56 until later production. Those older Colts have a Colt 5.56 chamber and are safe to shoot 5.56 ammunition as long as the rifle is a Colt factory unaltered rifle. If your buddy's rifle is an older Colt AR-15, it will be fine with the XM-193 5.56 ammo


This is gonna be where we make a final decision, I guess I need to check that as he is not very knowledgeable on this subject.
Where can I verify that on the barrel? Do I have to take anything apart or something? Anyone has pics?


The SP-1's also had a 1/12" twist barrel. M-193 will work fine in those. M-855 will not stabilize in the old 1/12" barrels. I believe that's when the barrels started to be marked 5.56 and give the twist rate on them when the Military adopted the M-855 round.

As far as you using the 5.56 ammo in your Savage XP bolt gun, the answer is NO. You need to use SAAMI spec 223 Remington ammunition in the XP.
Understood. thanks :)

I downloaded a copy of this some time ago for a handy reference

http://www.saami.org/specifications_and_information/publications/download/SAAMI_ITEM_211-Unsafe_Arms_and_Ammunition_Combinations.pdf

Another good read, thanks!

Where does it say .223? On the lower receiver or on the barrel near the flash suppressor? My preban R6500 had .223 on the lower receiver but 5.56 C MP 1/7 on the barrel, thats whats important.

Dave

We checked the receiver, we havent checked the barrel yet.

Thanks everyone.

kendog4570
09-14-2012, 9:05 PM
It's all internet horsechit, folks. Shoot it with either.

Roland Deschain
09-15-2012, 8:54 AM
This is gonna be where we make a final decision, I guess I need to check that as he is not very knowledgeable on this subject.
Where can I verify that on the barrel? Do I have to take anything apart or something? Anyone has pics?

My Colt CR6720 is stamped "MP 5.56 NATO 1/9 HBAR ELITE" on the top of the barrel at the front. Don't know if this a standard/common location for Colt to stamp their barrels but it would make sense to mark it in an uncovered location.

Searching images.google.com (http://images.google.com) for "colt ar barrel markings" shows some examples of top front marking and right side front markings.

17+1
09-15-2012, 9:07 AM
It's all internet horsechit, folks. Shoot it with either.

:iagree:

isplice
09-15-2012, 10:15 AM
Some Colt conversion kits from the 90's were marked "COLT 223" on the upper receiver, but had 5.56 barrels factory installed. I got one and it is a M4 upper receiver (has 4 stamped above the cloverleaf). I believe they did this after the 94 ban.