.223 v 5.56 brass Which to use

Mr Phil · March 6, 2009, 08:13 AM

I am still wet behind the ears in reloading.

I have seen and read vastly different opinions on .223 v 5.56 chamber differences and what to worry about or not.

Up until the present, I have shot only .223 chambered bolt-action varmint rifles and a Mini 14 so I have not worried about it and went with .223 across the board.

Now I have two new 5.56 chambered AR-15’s (LWRC)

What do I need to worry about regarding using .223 brass to reload for the 5.56 chamber?

I am getting ready to buy 5,000 cases so I want to get this right.

(Interestingly, I cannot find 5.56 labeled brass at Midway, Cabalas or CTD even listed ... although Midway had a single old discounted listing for Lake City 5.56 brass)

Am I also correct that once a .223 case is shot in a 5.56 chamber it would have fire formed into 5.56 and should not be used in .223 chamber?

Thanks in advance for the help.

wwmkwood · March 6, 2009, 08:50 AM

Besides the increase in presures the military uses in the 5.56, the case is slightly longer and needs to be trimmed to reload for the .223. Other wise the cartridges are identical.

kraigwy · March 6, 2009, 09:20 AM

Get the Wilson/Dillon/RCBS Case headspace gage to set up your sizing die to make sure the brass is sized to specs and you'll be fine using either in your rifles.

Mr Phil · March 6, 2009, 10:14 AM

Thanks Kraig - easy solution

**Unclenick** · March 6, 2009, 11:19 AM

As a practical matter, both 5.56 and 7.62 NATO brass is made with the same external dimensions as .223 and .308, so it fits those chambers when it is new. Longer military chambers and rapid extraction in full-auto fire can lengthen the once-fired stuff more than civilian arms do, but that has nothing to do with the new stuff.

Board member FALPhil has a good article you can search out to show the pressure differences between military ammo and commercial SAAMI maximums are actually very small. The main differences are apparent, only, being due to different measuring methods (the military persisted in using psi to mean cup for a long time) and the fact military ammo has to meet a velocity performance spec within a pressure band, while commercial ammo is loaded by pressure limits alone and is often loaded down well below the SAAMI maximum over liability concerns. Thus, it is milder just because it doesn't reach even the commercial maximum pressure, and not because a gun in good condition couldn't handle that maximum. The bottom line is that military ball ammo and match ammo fire just fine in civilian firearms.

When Compass Lake built my service rifle match AR they used a regular .223 match chamber. It shoots the military ball and match ammo just fine. The main difference in a 5.56 NATO chamber is it has a longer freebore so longer military special purpose ammo won't jam in its throat. Don't shoot special purpose military ammo in your civilian chamber without first measuring that its ogive seating depth is compatible.

totalloser · March 7, 2009, 02:33 AM

5.56 will need attention to the primer crimp. About 1 in 20 or so NEEDS attention, the rest do not. Set the decap to just barely push out the primers, and the ones that need the pocket reamed/swaged will stay in. All the hoopla about case weight in 5.56/.223 is just that. VERY little difference IME. You should trim/measure your cases always, anyhow.

Sooo, what to watch out for with 5.56: Machine gun fired brass will be HUGE and difficult to size. The MG chambers are big, so the brass gets big. That's what I use (thousands of pieces already) and the extractor marks can be ugly. Functional but occasionally pesky (hanging up in the shell plate in my progressive) Rolling the cases between 2 steel plates takes the ding down, but I have stopped bothering.

7.62x51 (military .308), on the other hand, IME all need a decrimp, and are thicker cases, requiring lower starting charges. "at least 5%" according to Speer.

Oh, and forget about fire forming for .223. The brass will be bigger than .223 from being fired, and will be sized back down by your die. The difference between 5.56/.223 is MINISCULE (maybe not even measureable) compared to the tolerances between sized/unsized brass.

March 6, 2009, 08:13 AM	#1
Mr Phil Member Join Date: January 23, 2009 Posts: 43	.223 v 5.56 brass Which to use I am still wet behind the ears in reloading. I have seen and read vastly different opinions on .223 v 5.56 chamber differences and what to worry about or not. Up until the present, I have shot only .223 chambered bolt-action varmint rifles and a Mini 14 so I have not worried about it and went with .223 across the board. Now I have two new 5.56 chambered AR-15’s (LWRC) What do I need to worry about regarding using .223 brass to reload for the 5.56 chamber? I am getting ready to buy 5,000 cases so I want to get this right. (Interestingly, I cannot find 5.56 labeled brass at Midway, Cabalas or CTD even listed ... although Midway had a single old discounted listing for Lake City 5.56 brass) Am I also correct that once a .223 case is shot in a 5.56 chamber it would have fire formed into 5.56 and should not be used in .223 chamber? Thanks in advance for the help. __________________ Don't bother running away ... you'll only die tired.

March 6, 2009, 09:20 AM	#3
kraigwy Senior Member Join Date: June 16, 2008 Location: Wyoming Posts: 11,061	Get the Wilson/Dillon/RCBS Case headspace gage to set up your sizing die to make sure the brass is sized to specs and you'll be fine using either in your rifles. __________________ Kraig Stuart CPT USAR Ret USAMU Sniper School Distinguished Rifle Badge 1071

March 6, 2009, 10:14 AM	#4
Mr Phil Member Join Date: January 23, 2009 Posts: 43	Thanks Kraig - easy solution __________________ Don't bother running away ... you'll only die tired.

March 6, 2009, 11:19 AM	#5
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	As a practical matter, both 5.56 and 7.62 NATO brass is made with the same external dimensions as .223 and .308, so it fits those chambers when it is new. Longer military chambers and rapid extraction in full-auto fire can lengthen the once-fired stuff more than civilian arms do, but that has nothing to do with the new stuff. Board member FALPhil has a good article you can search out to show the pressure differences between military ammo and commercial SAAMI maximums are actually very small. The main differences are apparent, only, being due to different measuring methods (the military persisted in using psi to mean cup for a long time) and the fact military ammo has to meet a velocity performance spec within a pressure band, while commercial ammo is loaded by pressure limits alone and is often loaded down well below the SAAMI maximum over liability concerns. Thus, it is milder just because it doesn't reach even the commercial maximum pressure, and not because a gun in good condition couldn't handle that maximum. The bottom line is that military ball ammo and match ammo fire just fine in civilian firearms. When Compass Lake built my service rifle match AR they used a regular .223 match chamber. It shoots the military ball and match ammo just fine. The main difference in a 5.56 NATO chamber is it has a longer freebore so longer military special purpose ammo won't jam in its throat. Don't shoot special purpose military ammo in your civilian chamber without first measuring that its ogive seating depth is compatible. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

March 7, 2009, 02:33 AM	#6
totalloser Senior Member Join Date: October 19, 2007 Location: Fort Bragg, CA Posts: 679	5.56 will need attention to the primer crimp. About 1 in 20 or so NEEDS attention, the rest do not. Set the decap to just barely push out the primers, and the ones that need the pocket reamed/swaged will stay in. All the hoopla about case weight in 5.56/.223 is just that. VERY little difference IME. You should trim/measure your cases always, anyhow. Sooo, what to watch out for with 5.56: Machine gun fired brass will be HUGE and difficult to size. The MG chambers are big, so the brass gets big. That's what I use (thousands of pieces already) and the extractor marks can be ugly. Functional but occasionally pesky (hanging up in the shell plate in my progressive) Rolling the cases between 2 steel plates takes the ding down, but I have stopped bothering. 7.62x51 (military .308), on the other hand, IME all need a decrimp, and are thicker cases, requiring lower starting charges. "at least 5%" according to Speer. Oh, and forget about fire forming for .223. The brass will be bigger than .223 from being fired, and will be sized back down by your die. The difference between 5.56/.223 is MINISCULE (maybe not even measureable) compared to the tolerances between sized/unsized brass. __________________ You only truly believe in freedom if you believe in the freedom of those you disagree.

March 6, 2009, 08:50 AM	#2
wwmkwood Senior Member Join Date: December 24, 2008 Location: Kansas Posts: 110	Besides the increase in presures the military uses in the 5.56, the case is slightly longer and needs to be trimmed to reload for the .223. Other wise the cartridges are identical.