.223 / 5.56 Cases

[tomme boy]

Fired brass is not the same as TRIM LENGTH. The only differance between the 223 an 5.56 chamber is the throat. 5.56 has a long throat to lesson the psi. 5.56 runs at a higher psi than 223, that is why the long throat. Consider the 5.56 like a Weatherby chambering.

[303Guy]

In my experience with .223 cases, PMP & RORG headstamp cases have much smaller capacity than the rest.

PMP 303 Brit brass also has less capacity than other brands. A lot less!

[nicholst55]

Fired brass is not the same as TRIM LENGTH. The only differance between the 223 an 5.56 chamber is the throat. 5.56 has a long throat to lesson the psi. 5.56 runs at a higher psi than 223, that is why the long throat. Consider the 5.56 like a Weatherby chambering.

You're absolutely right - my point is merely that once-fired 5.56mm brass tends to be significantly longer than once-fired commercial .223 brass.

[tomme boy]

Because of the higher psi. That would be why it would be longer.

[Gunnut 45/454]

tomme boy
I suggest you take a .223 Rem and a 5.56mm load and look at them side by side -the 5.56mm is a longer case! It comes out to about .010" and this is why when I load 5.56mm I trim to 1.760" not the .233 Rem trim length of 1.750" this allows the extra 1-1.5gr powder charge above the manuals with out compression!
IE true 5.56mm loads!

[tomme boy]

Gun, the length of the neck has nothing to do with internal capacity of either case. If you think it does you should not be reloading.

Also every manual made shows the trim length at 1.75" So if you are trimming to 1.76, you are wasting your time. Trim them to 1.75 and you will be able to fire them 2x's before you have to trim them again.

Myself, I don't trim anymore. I have so many extra cases, I load them once and fire them. I just take them to the scrap yard.

[badbob454]

tommie boy maybe you should re think this, a longer caseneck allows the bullet to be seated further from the base, allowing more powder area .. me thinks

[tomme boy]

Not if the OAL is the same between the two. If the OAL gained the .01" along with the neck length then I could see the added space. But just the neck being longer will not add space. The Mil brass is not ment to be reloaded and no thought is given for it. If the added length is real, I don't believe it. It does not really matter anyway as each gun is going to have a little differant chamber length. Make a cast of your chamber an see what it really is. 1.76 is the suggested max.

I lined up 20 differant 5.56 cases and it looked like waves on the ocean for the neck length. 55an 62 grain was looked at. Then I lined up some factory and they did vary but not as bad as the Mil. Remember, the ammo was made by the lowest bidder. As long as it goes bang and does not blow up the gun it is good enough for the Military. They would have to really try to mess things up to not meet the I think 4 MOA standard.

[Gunnut 45/454]

tomme boy
Ah been reloading for 30 plus years! Are you dening the facts as I posted? The 5.56mm case is longer-period! This is why you don't shoot 5.56mm in a .223 Rem chamber! Cause you'll be shoving that case into the throat area and this is why it can blow the gun-causes extreme pressure spike! Ever look at the ORIGINAL spec sheet on the 5.56mm? It was a 60,000psi cartridge! They have revised it down to a 55,000 psi round thats still 5,000 psi over the SAMMI spec for .233 Rem.
SAMMI still warns against firing 5.56mm in a .223Rem chamber do they not!

OK here are two more pics two different makes of 5.56mm I also have IMI if you need that for comparision!!! Are you still going to deny that 5.56mm is longer then .223Rem? And before anyone flaps there gums -NO I didn't cherry pick these rounds all were just pulled out of BRAND new box or off a stripper clip.

[tomme boy]

I'm not dening anything. Like I said, I lined up a bunch of 193 and 855 and the neck was all over the place for length. You just happen to have a consistant lot. Oh, and show me 1 instance of a 223 firearm that has blow up. And it is not the length of the neck that is differant. The throat is longer on 5.56. And it runs at a higher PSI.

I have heard the same thing from other reloaders. "I have been doing this for 30 years!!!!" That does not mean you know what you are doing. I have seen more people blow stuff up with 30 years reloading than some one that has been doing it for 6 months. The new reloader is very cautious about everything he does. Us older reloaders get very complacent about what we do. We know everything. Myself included.

[Gunnut 45/454]

tomme boy
Well you get yourself a nice tight chambered .223 Rem an shoot 5.56mm through and when it lets go don't come crying to me! I'll not do the search but I've seen the pics, read the stories behind not only bolt guns but AR's chambered in .223 Rem letting go. SAMMI says not to shoot 5.56mm in .223 Rem chambered gun- I think they know what they are talking about. Read an article on it and someone actually pressure tested it and on average a 5.56mm ran into 87,000 psi in a .223Rem chamber- do you feel lucky!

[tomme boy]

Like I said, Show me one gun that was blown up by shooting a 556 in a 223 gun. When a AR lets go, it was from having the wrong powder, or metal fatiuge of the bolt or extension, or a blockage.

And I had a Savage FP10 that I had Fred at Sharp Shooters Suppy do a complete build for me about 3 years ago. It was in 223 Rem with a Rock Creek 5R Stainless barrel with a 1 in 9 twist. It was throated to run Sierra 69gr MK. Head space was set at Very min. I ran 50 rounds of LC 01 M193 threw it just becuse that was all I had that day. Shot right at 1" No hard bolt lift. No ejector mark or any kind of marks on the case head.

[badbob454]

tomme boy , i agree the oal will give you the same capacity , . period i too shoot 556 in my .223 handi rifle and have never had to push the round into chamber no problems maybe the chamber is made longer to accept the .223 and 556 as many think the 2 are identical , this would be smart on the gunmakers part ... ..
here is a must read for us that have a .223 cal. only rifle
http://www.ar15armory.com/forums/556...Ch-t22582.html

[Idaho Sharpshooter]

Am I the only one here that missed the charge weight being for all ten? I don't think my 22-378Wby AI cases will hold THAT much powder...

Rich

Nice Hi-jack by the way