5.56x45mm vs .223 Remington - Page 2

MattLarson · June 26th, 2009, 07:45 AM

.223 Remington maximum safe chamber pressure is ~ 50,000 psi.
5.56 maximum safe chamber pressure is ~ 60,000 psi.

In addition, shooting 5.56 in a .223 chamber may cause significant increases in pressure due to the difference in chamber dimensions.

Do not shoot 5.56mm NATO-spec ammo in a .223 Remington chamber.

There's a ton of good info on this on the net. Here's just one of the many articles out there: The Gun Zone -- SAAMI on 5.56 v. .223 Remington

Matt

KevinDooley · June 26th, 2009, 10:35 AM

Quote:

Originally Posted by Ram Rod

Bushmaster makes only 5.56 NATO chambers for their AR-15's. I have a 1/9 twist barrel. It's plainly marked.

But they're not really 5.56, that's the point. Here's a post by an armorer for a security company. The high ups chose Bushmaster and he's had to ream every single chamber... There's another more in depth post about it, but I can't find it. Here he talks about new barrels the bean counters bought him that had the same (and other problems).

What they mark them and what they will actually shoot are two different things...

aus71383 · June 27th, 2009, 01:02 AM

Basically the dimensions of the cartridges are the same - the chambers are the same, but the differences are in thr throat, freebore and leade dimensions. The design of the 5.56 chamber helps reduce the pressure spike as the bullet reaches the leade, but is slightly less accurate (at least in theory).

Austin

Sig 210 · June 27th, 2009, 07:22 PM

There are several myths concerning military 5.56mm ammo. It is a myth that US made 5.56mm cases are thicker than commercial cases. For over 40 years I have weighed my cases when real good accuracy is desired. See the link below for case weights.

It is also a myth that 5.56mm military ammo is loaded to much higher pressure than commercial .223 ammo. US military 5.56mm ammo is loaded to 52,000 Psi + 3 standard deviations; not to exceed 58,000 psi. SAAMI specs are 55,000 psi.

SAAMI pressures

BTW: There are at least a dozen different .223 chambers. Unless your rifle is an H@R Handi rifle or it has a tight .223 match chamber there are no problems with firing 5.56mm military ammo in that gun. H@R re-ground their reamers and their chambers are all over the place from huge to very tight.

A gunsmith friend says that he knows of no US firearm maker who currently uses a SAAMI chamber for the .223.

This is a good link to peruse:

AR15BARRELS.COM - Technical Documents

Ram Rod · June 27th, 2009, 07:31 PM

Quote:

Originally Posted by Sig 210

There are several myths concerning military 5.56mm ammo. It is a myth that US made 5.56mm cases are thicker than commercial cases. For over 40 years I have weighed my cases when real good accuracy is desired. See the link below for case weights.

It is also a myth that 5.56mm military ammo is loaded to much higher pressure than commercial .223 ammo. US military 5.56mm ammo is loaded to 52,000 Psi + 3 standard deviations; not to exceed 58,000 psi. SAAMI specs are 55,000 psi.

SAAMI pressures

BTW: There are at least a dozen different .223 chambers. Unless your rifle is an H@R Handi rifle or it has a tight .223 match chamber there are no problems with firing 5.56mm military ammo in that gun. H@R re-ground their reamers and their chambers are all over the place from huge to very tight.

A gunsmith friend says that he knows of no US firearm maker who currently uses a SAAMI chamber for the .223.

This is a good link to peruse:

AR15BARRELS.COM - Technical Documents

Thank you......I'm now done replying to these types of threads.

Eagleks · June 28th, 2009, 02:33 AM

It's like saying should I buy a .357 or a .38, you can shoot .38 spls out of a .357. Shooting .38's out of a .357 is no more or less accurate... then shooting them out of a .38 gun. Same goes for .223 and 5.56.

The 5.56, as with the .357, has more "pressure" when shot ... so takes a barrel made to handle it. That's all.

Thanis · June 28th, 2009, 06:02 AM

Quote:

Originally Posted by Eagleks

It's like saying should I buy a .357 or a .38, you can shoot .38 spls out of a .357. Shooting .38's out of a .357 is no more or less accurate... then shooting them out of a .38 gun. Same goes for .223 and 5.56.

The 5.56, as with the .357, has more "pressure" when shot ... so takes a barrel made to handle it. That's all.

Ya, but there is an added (obvious) problem with the comparison as you could chamber a 5.56 in a .223...while you can't chamber a .357 Mag in a .38 Spl.

I keep going back and forth, if I'll evey buy an AR-15.

If I do, knowing what I do now, it would be a 5.56.

MattLarson · June 28th, 2009, 07:10 AM

Quote:

Originally Posted by Eagleks

It's like saying should I buy a .357 or a .38, you can shoot .38 spls out of a .357. Shooting .38's out of a .357 is no more or less accurate... then shooting them out of a .38 gun. Same goes for .223 and 5.56.

The 5.56, as with the .357, has more "pressure" when shot ... so takes a barrel made to handle it. That's all.

No, it isn't. There are critical dimensional differences between the 5.56 and .223 chambers.

Bottom line - firing 5.56 in a .223 chamber means you are firing the wrong ammo. You might get away with it, or you might seriously damage your rife (and / or yourself).

Matt

Sig 210 · June 28th, 2009, 07:36 AM

Quote:

Bottom line - firing 5.56 in a .223 chamber means you are firing the wrong ammo. You might get away with it, or you might seriously damage your rife (and / or yourself).

In 1968 I acquired a huge quantity of 5.56mm ammo. Had my Sako re-chambered to .223 at that time. That gun and several others that I own have digested thousands of rounds of 5.56mm ammo without a bauble.

SAAMI represents US commercial ammunition manufacturers. They waited 20 years until 5.56mm military ammo had flooded the market to spring this revelation on us. This is the same SAAMI that asked the BATF for a revision of ammo manufacturing and storage rules and then whined to high heaven when trhe BATF did just that.

MattLarson · June 28th, 2009, 08:08 AM

It's still using ammo in a firearm marked for a different ammo.

If one wants to take that risk personally, fine. Advising others to do so, IMHO, is a bit reckless.

Clint McKee of Fulton Armory (fairly well known as a knowledgeable guy in the firearms field) describes using shooting 5.56 in a .223 chamber as "Very Dangerous". It's not just pressure levels, it's the depth of the lede.

SAAMI to this very day lists shooting mil-spec 5.56 in a .223 marked firearm as an "unsafe arms and ammunition combination": SAAMI | Unsafe Arms and Ammunition Combinations

Matt

June 26th, 2009, 07:45 AM	#11
MattLarson Moderator Join Date: Nov 2005 Location: Central Florida Posts: 2,832	.223 Remington maximum safe chamber pressure is ~ 50,000 psi. 5.56 maximum safe chamber pressure is ~ 60,000 psi. In addition, shooting 5.56 in a .223 chamber may cause significant increases in pressure due to the difference in chamber dimensions. Do not shoot 5.56mm NATO-spec ammo in a .223 Remington chamber. There's a ton of good info on this on the net. Here's just one of the many articles out there: The Gun Zone -- SAAMI on 5.56 v. .223 Remington Matt __________________ Hope is not a plan.

June 28th, 2009, 08:08 AM	#20
MattLarson Moderator Join Date: Nov 2005 Location: Central Florida Posts: 2,832	It's still using ammo in a firearm marked for a different ammo. If one wants to take that risk personally, fine. Advising others to do so, IMHO, is a bit reckless. Clint McKee of Fulton Armory (fairly well known as a knowledgeable guy in the firearms field) describes using shooting 5.56 in a .223 chamber as "Very Dangerous". It's not just pressure levels, it's the depth of the lede. SAAMI to this very day lists shooting mil-spec 5.56 in a .223 marked firearm as an "unsafe arms and ammunition combination": SAAMI \| Unsafe Arms and Ammunition Combinations Matt __________________ Hope is not a plan.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

June 27th, 2009, 01:02 AM	#13
aus71383 Distinguished Member Join Date: Jan 2007 Location: United States Posts: 1,863	Basically the dimensions of the cartridges are the same - the chambers are the same, but the differences are in thr throat, freebore and leade dimensions. The design of the 5.56 chamber helps reduce the pressure spike as the bullet reaches the leade, but is slightly less accurate (at least in theory). Austin

June 27th, 2009, 07:22 PM	#14
Sig 210 Senior Member Join Date: Oct 2006 Location: Southwestern OK Posts: 797	There are several myths concerning military 5.56mm ammo. It is a myth that US made 5.56mm cases are thicker than commercial cases. For over 40 years I have weighed my cases when real good accuracy is desired. See the link below for case weights. It is also a myth that 5.56mm military ammo is loaded to much higher pressure than commercial .223 ammo. US military 5.56mm ammo is loaded to 52,000 Psi + 3 standard deviations; not to exceed 58,000 psi. SAAMI specs are 55,000 psi. SAAMI pressures BTW: There are at least a dozen different .223 chambers. Unless your rifle is an H@R Handi rifle or it has a tight .223 match chamber there are no problems with firing 5.56mm military ammo in that gun. H@R re-ground their reamers and their chambers are all over the place from huge to very tight. A gunsmith friend says that he knows of no US firearm maker who currently uses a SAAMI chamber for the .223. This is a good link to peruse: AR15BARRELS.COM - Technical Documents

June 28th, 2009, 02:33 AM	#16
Eagleks Distinguished Member Join Date: May 2008 Location: Kansas Posts: 1,686	It's like saying should I buy a .357 or a .38, you can shoot .38 spls out of a .357. Shooting .38's out of a .357 is no more or less accurate... then shooting them out of a .38 gun. Same goes for .223 and 5.56. The 5.56, as with the .357, has more "pressure" when shot ... so takes a barrel made to handle it. That's all.