5.56 into .223

rickdavis81 · January 25, 2008, 01:33 PM

I traded my 5.56 upper for a .223 upper. Now I have tons of brass laying around. Is it safe to use the 5.56 brass to load for my .223. I've heard of different case thickness and am worried about to much pressure.

ibfestus · January 25, 2008, 02:14 PM

As long as you are full length resizing and you work up your load from scratch.

Master Blaster · January 25, 2008, 02:36 PM

5.56 is a looser chamber specification than .223. The problem arises when you have a 5.56 round that is too long for the .223 chamber, and is loaded to maximum military performance 2000-4000 psi over .223 saami spec. This results in the bullet ogilvie being jammed into the rifling ( a 5.56 chamber has a longer lead to accomodate the longer bullets), and the round is already 2000 psi higher pressure, so you could have a big time over pressure situation in that .223 chamber.

Most military 5.56 ammo is just fine in a .223 chamber, but there is some small percentage of military ammo that is overlength and over pressure for a .223.

To know if this is a problem in your rifle you could measure the headspace, if its loose no problem but if its tight (match chamber on a bolt action) it COULD be a problem.

If you are loading your own you have control of bullet, OAL, and charge weight so it should never be a problem if you start out low and work up as you always should.

Tim R · January 26, 2008, 07:17 AM

I prefere Lake City brass for use in my match AR's. Full size 'em and load 'em.

Alleykat · January 26, 2008, 10:09 AM

Quote:

5.56 is a looser chamber specification than .223. The problem arises when you have a 5.56 round that is too long for the .223 chamber, and is loaded to maximum military performance 2000-4000 psi over .223 saami spec. This results in the bullet ogilvie being jammed into the rifling ( a 5.56 chamber has a longer lead to accomodate the longer bullets), and the round is already 2000 psi higher pressure, so you could have a big time over pressure situation in that .223 chamber.

Most military 5.56 ammo is just fine in a .223 chamber, but there is some small percentage of military ammo that is overlength and over pressure for a .223.

To know if this is a problem in your rifle you could measure the headspace, if its loose no problem but if its tight (match chamber on a bolt action) it COULD be a problem.

Accurate information. However, largely irrelevant to his thread. When you run the 5.56 brass through the .223 die, you have the same spec brass as .223 brass. FWIW, military 5.56 brass has the same case capacity as commercial .223 brass. Not true with .308, however.

rickdavis81 · January 26, 2008, 08:35 PM

Sounds good. Thanks for the info on the .308, I have on of those too but only use .308 brass so far.

CrustyFN · January 26, 2008, 09:22 PM

Yep, what Alleykat said.
Rusty

January 25, 2008, 01:33 PM	#1
rickdavis81 Senior Member Join Date: April 3, 2006 Location: Missouri Posts: 398	5.56 into .223 I traded my 5.56 upper for a .223 upper. Now I have tons of brass laying around. Is it safe to use the 5.56 brass to load for my .223. I've heard of different case thickness and am worried about to much pressure.

January 25, 2008, 02:14 PM	#2
ibfestus Senior Member Join Date: October 21, 2006 Location: Smack dab in the middle of it... The good ol' USA that is. Posts: 126	It is OK, BUT As long as you are full length resizing and you work up your load from scratch.

January 26, 2008, 07:17 AM	#4
Tim R Senior Member Join Date: November 30, 2004 Location: God's side of Washington State Posts: 1,601	I prefere Lake City brass for use in my match AR's. Full size 'em and load 'em. __________________ God Bless our Troops especially our Snipers.

January 26, 2008, 09:22 PM	#7
CrustyFN Senior Member Join Date: June 4, 2006 Location: West Virginia Posts: 2,258	Yep, what Alleykat said. Rusty __________________ I don't ever remember being absent minded.

January 25, 2008, 02:36 PM	#3
Master Blaster Senior Member Join Date: October 11, 1999 Location: One of the original 13 Colonies Posts: 2,281	5.56 is a looser chamber specification than .223. The problem arises when you have a 5.56 round that is too long for the .223 chamber, and is loaded to maximum military performance 2000-4000 psi over .223 saami spec. This results in the bullet ogilvie being jammed into the rifling ( a 5.56 chamber has a longer lead to accomodate the longer bullets), and the round is already 2000 psi higher pressure, so you could have a big time over pressure situation in that .223 chamber. Most military 5.56 ammo is just fine in a .223 chamber, but there is some small percentage of military ammo that is overlength and over pressure for a .223. To know if this is a problem in your rifle you could measure the headspace, if its loose no problem but if its tight (match chamber on a bolt action) it COULD be a problem. If you are loading your own you have control of bullet, OAL, and charge weight so it should never be a problem if you start out low and work up as you always should.

January 26, 2008, 08:35 PM	#6
rickdavis81 Senior Member Join Date: April 3, 2006 Location: Missouri Posts: 398	Sounds good. Thanks for the info on the .308, I have on of those too but only use .308 brass so far.