Firing 5.56 in a .223 chambered rifle
Firearm & Gun Forum - FireArmsTalk.com > Long Guns > Auto & Semi-Auto Discussion > Firing 5.56 in a .223 chambered rifle

Reply
 
LinkBack Thread Tools Display Modes
Old 09-29-2011, 06:54 AM   #1
Feedback Score: 0 reviews
 
RufusTFirefly's Avatar
 
Join Date: Sep 2011
Location: Tucson,AZ
Posts: 127
Liked 2 Times on 2 Posts
Likes Given: 7

Default Firing 5.56 in a .223 chambered rifle

I own an FNC semi-auto that is stamped "CAL. 223 REM SPORTER". Now the Belgian military FNC is chambered for 5.56 NATO. I got a gonga deal on 2,000 rds of 5.56 many years ago and have been firing those thru the FNC ever since. I was always under the impression that the two rounds were identical.

Now I am reading that there is a *slight" difference in the chamber dimensions of .223 weapons and 5.56 weapons- and that higher than acceptable pressures can occur if 5.56 is fired in a weapon chambered for .223.

So what do you all say? Is this overreactive hype? or should I be concerned?

Thanks,

Rufus

__________________
RufusTFirefly is offline  
 
Reply With Quote

Join FirearmsTalk.com Today - It's Free!

Are you a firearms enthusiast? Then we hope you will join the community. You will gain access to post, create threads, private message, upload images, join groups and more.

Firearms Talk is owned and operated by fellow firearms enthusiasts. We strive to offer a non-commercial community to learn and share information.

Join FirearmsTalk.com Today! - Click Here


Old 09-29-2011, 12:03 PM   #2
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
303tom's Avatar
 
Join Date: Sep 2011
Location: Missouri
Posts: 3,645
Liked 1212 Times on 827 Posts
Likes Given: 1222

Default

They are the same round, one military & one civilian !!!!!!!!!!

__________________

When all else fails.

303tom is offline  
 
Reply With Quote
Old 09-29-2011, 01:08 PM   #3
Feedback Score: 0 reviews
 
neilage66's Avatar
 
Join Date: Jul 2011
Location: FEMA,Region V
Posts: 630
Liked 3 Times on 3 Posts

Default

From wiki: .223 Remington - Wikipedia, the free encyclopedia

Quote:

The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a .224" diameter, jacketed bullet, with weights ranging from 40 up to 90 grains, though the most common loadings by far are 55 grains.

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive leade. [3] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[4] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56 mm ammunition.
__________________
Yesterday is history, tomorrow is a mystery and today...today is a gift.

Be Well.
neilage66 is offline  
 
Reply With Quote
Old 09-29-2011, 01:35 PM   #4
Feedback Score: 0 reviews
 
canebrake's Avatar
 
Join Date: Jan 2009
Location: 150 miles NE of Sloppy Joe's Bar
Posts: 21,941
Liked 1419 Times on 808 Posts
Likes Given: 1290

Default

They are NOT the same.



Call FN and ask them.

__________________
http://i695.photobucket.com/albums/v...brake02jpg.jpg

http://i1060.photobucket.com/albums/...ps18cfbeae.jpg

Get her dirty, then clean her so she starts to respect you. When her trust is complete, she will serve you well for a lifetime!

"...if doves shot back, there wouldn't be a need for a bag limit."
- orangello
canebrake is offline  
 
Reply With Quote
Old 09-29-2011, 01:42 PM   #5
Feedback Score: 0 reviews
 
Yunus's Avatar
 
Join Date: Jan 2009
Location: |,Maryland
Posts: 4,808
Liked 1109 Times on 657 Posts
Likes Given: 348

Default

303tom, would you please edit your post. They are not the same round and someone searching via google with this same question might come across this thread and see your reply. They are similar but it's dangerous to shoot a 5.56 round in a .223 chambered firearm.

__________________

"Good people drink good beer."
Hunter S. Thompson

Yunus is online now  
 
Reply With Quote
Old 09-29-2011, 02:36 PM   #6
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
303tom's Avatar
 
Join Date: Sep 2011
Location: Missouri
Posts: 3,645
Liked 1212 Times on 827 Posts
Likes Given: 1222

Default

No i won`t !

400px-.223_remington.jpg   400px-5.56x45mm_nato.jpg  
__________________

When all else fails.

303tom is offline  
 
Reply With Quote
Old 09-29-2011, 02:43 PM   #7
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
303tom's Avatar
 
Join Date: Sep 2011
Location: Missouri
Posts: 3,645
Liked 1212 Times on 827 Posts
Likes Given: 1222

Default

Quote:
Originally Posted by canebrake View Post
They are NOT the same.



Call FN and ask them.
Yes there is a difference between the military & civilian chamber, the military chamber is roomier to accommodate trash.
__________________

When all else fails.

303tom is offline  
 
Reply With Quote
Old 09-29-2011, 02:47 PM   #8
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
303tom's Avatar
 
Join Date: Sep 2011
Location: Missouri
Posts: 3,645
Liked 1212 Times on 827 Posts
Likes Given: 1222

Default

And before you get started on the thickness of the military case, yes they are that is to accommodate rough handling so you don`t have a bunch of dented up cases.

__________________

When all else fails.

303tom is offline  
 
Reply With Quote
Old 09-29-2011, 03:21 PM   #9
Feedback Score: 0 reviews
 
Yunus's Avatar
 
Join Date: Jan 2009
Location: |,Maryland
Posts: 4,808
Liked 1109 Times on 657 Posts
Likes Given: 348

Default

Quote:
Originally Posted by 303tom View Post
They are the same round, one military & one civilian !!!!!!!!!!
Quote:
Originally Posted by 303tom View Post
Yes there is a difference between the military & civilian chamber, the military chamber is roomier to accommodate trash.
Quote:
And before you get started on the thickness of the military case, yes they are that is to accommodate rough handling so you don`t have a bunch of dented up cases.
Well at least your willing to contradict yourself in the same thread.

Also as was posted by neilage66 and the OP there are pressure differences.
__________________

"Good people drink good beer."
Hunter S. Thompson

Yunus is online now  
 
Reply With Quote
Old 09-29-2011, 03:40 PM   #10
Moderator
FTF_MODERATOR.png
Feedback Score: 0 reviews
 
JonM's Avatar
 
Join Date: Nov 2009
Location: Rochester WI,Rochester WI
Posts: 17,586
Liked 5677 Times on 2964 Posts
Likes Given: 375

Default

Quote:
Originally Posted by 303tom View Post
the military chamber is roomier to accommodate trash.
Thats not true. I went through armourer school and it pretty much detailed the wiki article so much in fact i think they got the wiki info from the military training manuals.

Quote:
Originally Posted by 303tom View Post
And before you get started on the thickness of the military case, yes they are that is to accommodate rough handling so you don`t have a bunch of dented up cases.
The thickness is not to promote rough handling the military doesnt reload. Military brass is recycled or left on the battlefield. Recycled brass the military sends back is melted to make new cases. The thickness is to prevent case failure due to the higher pressure loading of the 5.56 cartridge.

Im not sure where you are getting your info. But the two are not the same at all. Ive personally seen two kabooms in the last decade from using nato surplus in civvy ar15 chambered for 223.

Military 556 in 55 grn loading hits nearly 3200fps civvy 223 can barely reach 2900 fps in safe loadings.

Military chambers have a long lead so they can use tracer ammo safely which has a greater bullet length than the same weight bullet in fmj format. Accuracy in military arms is not the main goal so a little extra bullet jump to hit the lands is not a big deal if the thing shoots 3 inches instead of 2.
__________________

"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

JonM is offline  
 
Reply With Quote
Reply

Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Firearms Forum Replies Last Post
S&W mod 1955 chambered in .45 cal Bolchben General Handgun Discussion 7 04-24-2011 03:21 AM
6.5x47 Lapua re-chambered to 260 Rem hyatus44 Gunsmithing Forum 0 10-27-2010 02:04 AM
Is there a commercially chambered 4mm rimfire?? MoAmmoPlease .22 Rifle/Rimfire Discussion 5 04-11-2010 03:11 AM
Chambered Revolver notdku Concealed Carrying & Personal Protection 21 04-08-2010 02:52 AM
What other rifles are chambered for 7.62x54r? supergus Curio & Relic Discussion 12 07-01-2009 01:43 PM